From Muppet Wiki

Marie Dodo is a member of the Dodo family in Follow That Bird.

The daughter of Daddy Dodo and Mommy Dodo, Marie is just as muddleheaded as the rest of her family, if a bit more childish. She has a sibling rivalry with Donny Dodo, and seems at best only dimly aware of new foster brother Big Bird. Neither Marie nor Donny can grasp the concept of pretending, pretending only to be themselves.

Donny and Marie's names are a reference to the pop duo Donny and Marie Osmond.

Marie also appeared in The Muppets: A Celebration of 30 Years.