So you can't see how students will be influenced seeing a fellow student(who they may be friends with and go to sleep overs, social functions, etc) with lesbian parents. Give me a break.
I don't understand what influence you are concerned about. The only I can think of is that they lesbians would attempt to seduce the daughter's friends, is that what you mean? Or is it that the kids will see that there are lesbian couples and be more inclined to see that as normal?
You were not specific.