Don't confuse the two issues. Daughter has linked the two things. And they are not dependent on each other. A yes or no answer is all that is required from her.
You want her to babysit as a contributing member of the family. An expectation that she has as the oldest child in the family who has the ability to provide support to her parents.
Your daughter saying no is fine. You will find alternative.
Her having sex with a partner in your home is not something that she can use to negotiate with. Sex is not a commodity. And the mere fact she has used it in this manner, tells me she lacks the maturity to have been provided with this privilege in your home. Because that is what it is.
You using it a point of negotiation is not ok either. G the horse has already bolted in this case. She already has wife's permission to engage in this activity in your home. No point drawing a line now. It will just be perceived as punishment by daughter if she says no to your request.
You don't need to, nor in my opinion should you accept her terms and conditions. Frankly if she wants to be adult, move out of the house and do as you please. Don't contribute to the family functioning at all.
I would simply say that you will accept her response as no and leave it that.
There is absolutely no point your trying to parent her and put boundaries in place now. It's too late. To be frank as parents you have been permissive with oldest daughter and you are now reaping the cost of this permissiveness.
Just my two cents worth G, (and to be completely honest I want to bang you and wife's heads together) Aaarrrrgghhhh! Sorry G, my personal frustration showing.
