I think it is way too soon for Robin/Roland to be on the family tree because of a marriage with Regina. She did however have cousins possibly with the whole Xavier line and maybe Marian was one of those! That would mean Roland could be genetically related to Regina (the kid playing Roland is hispanic too I think, like Xavier and Henry. Sr, and of course Lana). More of the wreath of a family tree business.
The other I think is going to be Charming’s dad as he’s been missing and they need to have a charming centric story, which works welll with Ginny’s pregnancy, and Charming realizing he is going to be a dad again, which might be good for backstory parallel to his own father.
I’m pretty sure the article said beyond PP and Snowing baby, so that’s why I think it has to be something or someone else.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass