Def mother and daughter stuff, alot of people were mentioning putting it behind the corruption route, I disagree it should really be like 3 choices, (maybe an extra or whatever).
1st) its the straight up cheating path, (while it can be hot not my cup of tea)
2nd) convincing her daughter to have the mother join in (my personal choice)
3rd) just a normal path no lewd or anything (kinda boring but not everyone likes to have both)
And you could maybe add an extra choice but these are just ones off the top of my head.