Board Thread:Spoilers!/@comment-1916997-20170725142404/@comment-25971187-20170728103023

Anastasia and Will, however, are in the same Enchanted Forest as Robin Hood and the other Merrymen, so unless Robin travelled realms in his robbery days and ended up in a different Enchanted Forest wherein there's another Maleficent (to be fair, we didn't see her), Anastasia and Drizella becoming sisters is unlikely.