Mel arrives home late and expects to be grounded by Brian and Sophie but isn't. She keeps trying to get into trouble until she comes home with a walkman she says she stole. Josh tries to get a date with Tanya Thomas (Zoe Thorne), so he enlists Brian's help. Brian morphs into Josh and asks out Tanya's friend, Denise, who fancies him. When the two girls meet each other on the day of the date, they both start hating Josh.

When Lucy calls Brian and Sophie "Mum and Dad", Mel gets angry and shows Lucy and Josh a box of things she kept to remind her of their real parents. However, a lipstick is missing from the box. Lucy realizes that it was she who had taken it and swapped it, so she must ask Josh for help. Meanwhile, after a string of Fs, Josh must resit his exams or be put back a year. To pay him back for helping with the lipstick, Lucy helps him revise, and discovers that he may be dyslexic.

Lucy discovers she and her best friend are 'geeks' after they are the only two girls in the class not to be invited to a party. Mel gives Lucy a makeover, but this threatens to alienate her from Wendy, with whom she has been studying caterpillars. Sophie is struck down with a case of the flu, but enjoys her freedom from housework and responsibility and hides her recovery. Lucy decides friendship is more important than being 'cool', and she and Wendy discover that their caterpillars "were really butterflies all along."

When Lucy wins tickets to see Blink 182 in a competition, Josh is desperate to take them off her hands – after all, he's a huge fan of the band, and Lucy's such a geek she's never even heard of Blink 182. Lucy agrees to give the tickets to Josh, but on one condition: Josh has to perform a truly unselfish deed in order to qualify for the tickets. Of course it's a terrible struggle for the scam-meister, but Josh learns a whole lot about himself in the process. Elsewhere Mel is upset (though refuses to show it) when Trent appears to be going on a date with another girl. The confusion is resolved later in the episode when it turns out that Kelly is Trent's cousin, not his date and he and Mel become friends again.

Lucy is selected to represent the school in a Science Tournament where she has to build a rocket with maximum propulsion – which proves to be too difficult a task for her, so Sophie offers to help. Brian enters one of Mel's photograph's in an art contest. Josh tries to bribe Scott Taylor into letting him join the football team and get to go to Holland and almost loses Frankie and Pete as friends.

Mel asks Scott Taylor to the school Christmas disco, causing Trent to get jealous. Lucy is cast as Mary in the Nativity play, a part Wendy wants. Josh fills Brian and Sophie in about Christmas. Lucy gives Wendy the part of Mary in the play, but Wendy becomes extremely demanding. Mel gets cold feet and won't go to the disco, so Brian morphs into her and goes in her place. Mel finds out and rushes to the disco, only to find Brian-Mel kissing Scott, right in front of a heart-broken Trent! Mel attempts to repair the damage caused by Brian, only to find out some things about herself. The school Nativity play becomes a strain on Lucy and Wendy's friendship. Josh has nightmares and is visited by ghosts in a plotline similar to that of Dickens A Christmas Carol.

Mel asks Scott Taylor to the school Christmas disco, causing Trent to get jealous. Lucy is cast as Mary in the Nativity play, a part Wendy wants. Josh fills Brian and Sophie in about Christmas. Lucy gives Wendy the part of Mary in the play, but Wendy becomes extremely demanding. Mel gets cold feet and won't go to the disco, so Brian morphs into her and goes in her place. Mel finds out and rushes to the disco, only to find Brian-Mel kissing Scott, right in front of a heart-broken Trent! Mel attempts to repair the damage caused by Brian, only to find out some things about herself. The school Nativity play becomes a strain on Lucy and Wendy's friendship. Josh has nightmares and is visited by ghosts in a plotline similar to that of Dickens A Christmas Carol.

Mel gets a job offer as an assistant to a fashion photographer. However, her audition takes place during school, so she goes to the audition whilst Sophie (who is not a very gifted morpher) morphs into Mel and goes to school. Unfortunately, she goes around kissing everyone, including Trent, Frankie and Mrs. Hardman. She is referred to a child psychologist. Sophie panics when seeing the psychologist and Mel arrives to take over. She soon transforms to a lady with Red hair to make sure the psychologist doesn't see there are two Mel's. However, Sophie cannot morph back to her original human form, and decides to keep another look, thus introducing a new looking Sophie (Carla Medonça).

Brian and Sophie become hooked on a trading card game, and will go to any lengths to obtain more cards. They end up stealing and selling the school laptop. They then discover there is a rare card (Madonna) that they need to find. They find the card, but realise they have wasted their time and money. They feel very silly.

Lucy discovers she has a talent for judo, and Brian thinks the only way to keep her as his friend is to tag along. Sophie then decides she wants to be Trent's friend. However, she later brings a live duck into the house to cook. Trent gets upset when he sees this and asks her what's going on. Mel tells him that Sophie is making a statement about vegetarianism, so he thinks they are vegetarians. Meanwhile, Lucy gets ready to go to Paris for a judo competition.

Brian and Sophie are not technically married, so Lucy arranges a wedding to bring the family closer together, but her grand ideas are nothing compared to Sophie's. Brian learns it is hard to choose a best man. When Mel gets angry about the wedding, they decide not to have a proper wedding, but a friendship ceremony instead.

It's Valentine's Day, and Josh is trying to get a date with Tanya Thomas, but makes the foolish mistake of taking Brian's advice on matters of the heart. Mel is the object of desire of Andy the Freak and Frankie when all she wants is a 'joke' Valentine's card from Trent. Sophie follows her heart and writes a card to her true love: the dishwasher. Sophie asks the family what Valentine's Day is, but in an episode a few years ago when Barbara Durkin played Sophie she is trying to act calm in front of a teacher who has come to visit the house and she says "This happened to me once on Val.... Valentine's Day".

An alarm sounds in the household – signaling that there is a Valux rescue ship nearby. Brian and Sophie are faced with a difficult decision: go home, or stay with the children. The children are horrified that they might be abandoned again and recall (in flashback) the day they were fostered by a very different-looking Brian and Sophie. Lucy was desperate for a family, Josh was still looking for fringe benefits and Mel was desperate to avoid disappointment. Can Brian and Sophie be persuaded to keep their family together?

Brian and Sophie adopt a new child: Howie. Howie turns out to be a safety freak, much to the exasperation of Mel, Josh and Lucy. Seeing their reaction, Howie runs away... and then the children's social worker comes to the house for Brian and Sophie's progress report. Due to objections from fans of the show saying that Howie was too annoying the character was discontinued after this one brief appearance.

On Father's Day, Sophie gets upset that she has never received any Mother's Day gifts. Brian sets out to prove he is the World's Best Dad. Josh tries to gain the new video game "Gnomes Of Vengeance" from the new girl, Poppy Manning, but she will only give games to girls. Josh asks Lucy to get the game from Poppy for him. Lucy agrees on one condition – that Josh pays her £54.60. Mel is upset when Brian thinks she is a boy. The episode concludes with Sophie attempting to be more masculine by working out and Brian attempting to become more feminine by growing breasts.

Continued from the previous episode. Brian and Sophie's attempts to embrace the opposite gender become more and more extreme. Brian tries to be a better father by becoming more sensitive, while Sophie gets in touch with her masculine side. Josh still attempts to get the video game from Poppy.

Brian feels rejected when Sophie chooses to watch repeats of Geoff Jefferson, Criminal Prosecutor, on cable TV, instead of taking part in his indoor Olympic Games. Josh also has grievances with Sophie's television hogging – the wrestling team have paid him in advance for tapes of special shows. This is not true. Lucy cuts the cable on the TV to end the suffering, but it ends up with Sophie putting Brian's pet rat on trial. Brian is devastated, so tries to put the blame on himself. Lucy then admits and ends up being captured and rescued on the same night.

Josh is woken by a trumpet-playing Brian and is offered tiddlywinks for breakfast. His sisters may be technically human but they still can't behave like normal people. Why can't his family just be different in every way? A bump on the head makes Josh's wish come true, throwing him into a world of complete opposites. Lucy is stupid, Mel cares about what she looks likes and fancies Frankie, Sophie doesn't even try to be a good mum, Pete is short and fancies Mel and Frankie is tall doesn't like Mel but all of the other girls fancy him. Wendy is his girlfriend and like Lucy, is thick, but more clumsier than Lucy. And Mrs. Hardman is the art teacher and fancies Brian. This leaves a whole world of confusion and he wishes that he could have been fostered by someone else.

Meanwhile, the opposite Lucy and Wendy, are trying to write a story to win a day with Chubby the Bear but don't write much. And when Sophie enters too, Josh has to stop her from entering.

Brian and Sophie learn about age concerns which leads them to either wanting to move in a retirement home or get wrinkles! Meanwhile, Josh's voice breaks and uses it to pretend he's Brian phoning school to say that Josh is ill.

Brian is out buying a bicycle, but ends up in a wheelchair. Not that he had been beaten up, but he loved the wheelchair and rejected the bicycle. Lucy overhears Wendy's Mum saying to Mrs. Hardman that Wendy only has four weeks to live. Meanwhile, Brian protests at the diner for disabled access and Mel is recovering from a mud mask that went horribly wrong and having to be guided round school by a guy called 'Francis'...which is actually Frankie!

Brian is still protesting for disabled access at the diner. But soon everyone notices that he is just lazy, until he actually has a wheelchair accident. Meanwhile Sophie changes places with the school rabbit so that Josh can get the reward money off Poppy Manning and Mel discovers that Francis is actually Frankie.

Josh, Pete and Frankie are in competition for the attention of a new girl in school, but there's a surprise in store for one of them when they discover who she is. Mel has left for Canada and Brian is suffering in her absence, so takes matters into his own hands by getting a 'new Mel' from the children's home, while Lucy is enjoying having a room to herself, which soon changes as CJ starts launching desperate attempts to move in, even resorting to 'becoming' a girl!

Josh and Brian vie to see which of them can tell the scariest Hallowe'en story, but Sophie can't understand why it's fun to be frightened.

Confused by ideas of right and wrong, Brian decides wrestling is the best way to settle arguments. Meanwhile, Sophie is given the opportunity to eavesdrop on Whiteside's private moments.

Mel finds out that the children have or had an aunt and uncle in Canada who look suspiciously like Brian and (the original) Sophie. They confront Brian and Sophie, who admit that, seven years ago, they met Josh, Mel and Lucy's aunt and uncle at the children's home – and then, after the aunt and uncle realized that they were aliens, the aunt and uncle were kidnapped and kept in suspended animation in the attic for seven years. The children insist that they let them free. Meanwhile, Wendy discovers Brian and Sophie are aliens, and she tells Pete and Frankie too, so Brian wipes their memories. Everyone realizes that it is time to move on. Josh, Mel, Lucy, Harry and CJ all move to Canada with the real Brian and Sophie Johnson, and the aliens appear to go back home to Valux; however, Brian presses the big red button that caused the pair to crash-land on Earth in the first place setting the stage for series 8. They land by the sea and then head for the foster home.