Please read over the collection guidelines, they should answer your question.

The new Muppets movies are sequels. They even refer to events in previous movies (as did some of the older films). These movies represent continuing adventures of the same characters. This even applies to the "historical" movies (e.g. Christmas Carol, Treasure Island) because a large part of the Muppets universe is a meta-awareness that their world is a show or performance. Muppets went meta before anybody else was doing it!