Hi! Thank you, kind comments are a big part of the motivation for developers. Now, to answer your questions:
1. Cousin, I will consider, because there is no short name for referring to the cousin's husband (cousin-in-law?), which happens a lot. Grandmother was so obvious I did not think about it. I will insert it in v 0.37. One thing that I want to specify, though, is that most of the times this only changes how the characters are referred to, so sometimes the result is not optimal, but it's the best I can do. (i.e. she says she has an age comparable to that of the character's mother. This works with landlady, all degrees of mom and aunt, but it's weird with sister and grandma.)
Also, the pics stay the same, and feminization is still possible, so it takes a big stretch to think that those in the pics are grandparents. This suspension of disbelief is actually very much requested for the game already, but sometimes people don't realize that, and complain about the silly situations/reactions/events.
2. I am not into ballbusting/cbt, so those are options that belong to Tier Imaginary Friend and above, if even (if anyone is in exactly for the Tier's commission, please contact me beforehand, so we can agree on the kinks and fetishes)
3. Yes, if I get to a point where prostate massage is a thing, it can definitely escalate to pegging.