Congrats on surrogacy-it's a wonderful gift.
For the rest-
I find it helpful to remind myself frequently-
We have control over only one person in this world-ourselves.
We can ask-but we have to always assume the other person COULD refuse to grant our request, COULD agree to grant it but fail to follow through, COULD refuse and follow through anyway, or COULD agree and follow through. I give it a 25% chance on each option (no statistics-that's just out of my ass because it's convenient for me to remember), which means there is a 75% chance that they are not going to agree and follow through on anything I request.
If I am not ok with that-then I need to make other arrangements.
So-in your example:
I wouldn't have sex with him if 75% failure to use condoms with others after agreeing to.
I wouldn't bother asking-because 75% would be too high of a risk to me in that scenario.
"Love As Thou Wilt"