beta
I saw some of the comments before reading it, there were a lot of people angry at the fact that they didn't do a DNA test. However, after reading it I sort of understand why she asked for that in her will. I feel like she realised that (sorry, I'm bad at remembering names), light haired guy like dark haired guy hence why she asked for both of them in her will instead of just one. In my opinion the dark haired guy is probably the dad, there personalities are practically the same, but then again nature vs nurture, so it could just be because of how meguru grew up.
Also, ririko (correct me if I'm wrong) knew that the black haired guy was going to be a bad father. She might have been like, 'why not kill two birds with one stone', if light haired guy liked dark haired guy they might be able to build a relationship whilst taking care of meguru. That way, all three wouldn't be lonely.