There are several issues overlapping at this point.
#1 is the abandonment issue, which from what we know from the story could have been worse than just leaving them in a forest, the parents could have sold the children as slaves.
#2 is the immigration one, the new village is barely creating its own identity and culture and having a bunch of people from another village come in might affect that, specially because there are emotional ties with the kids, as has been shown theres already 2 factions forming.
all in all, this a very interesting twist, I hope it doesnt get resolved in the story and just keeps creating drama that they have to deal with, but we all know this is an isekai and the MC is gonna BS his way out of it.