So a custom, really unneeded mechanic that is basically just put in due to fanservice should prioritize over marriage?
The only games where children were relevant are two games: Geneology and Awakening. Marriage has been technically in since the first game, even if its just in passing in endings, and its a part of supports.
Children have had their time to shine in a game already. Let same sex marriage take priority for once. Then after that we can maybe think about putting children in, and not as just adoption for an ending.