Ok I finally read through the whole thread. I think it might be a good tactic to say, sure, check it out! And hopefully she would realize that it would not be a good fit.
But I don't get why it can't be forbidden, even for an 18 yr. old. Unless they have enough money to pay the significant dues and other associated costs (believe me there are many) it seems pretty simple to not provide the money. Additionally, and I guess this is more of an issue for sons than daughters because most of the alcohol and partying is at fraternity houses, the fact that parents of members can be held liable when someone gets raped or injured or killed, makes it entirely reasonable IMO for parents to say no. See recent Atlantic article featuring a lawyer who specializes in suits against greek orgs.
I am fortunate in this issue because I cannot imagine a world in which my dd would be interested in pledging. Thankfully, because she will likely be going to our flagship state school where rush is brutal.
I would guess that this issue would sort itself out because it seems like it would become clear to your dd that she will more likely meet interesting friends through other means than greek life.
