MC gave them a list with many names, but feared it not being useful as they were all scandals in the future, thankfully the one that got the list was competent, the girl grandmother, and as she was already have her eyes on some of their names she investigated more and discovered some had indeed created problems, not everyone, but that was enough.
MC had even written the girl father name, he didn't knew who he was and was surprised from it.
The grandmother accepted MC info because the girl mother was friend with the MC one, so they thought his mom had investigated personally to help the heroine, as the 2 mothers had promised each other.
The thing makes sense because they would think MC and his mom had talked about it and he only had the names and the mother had the data.
I think that the chapter with the grandma will cover the names and stuff.