I have no personal experience in this; have done some reading on the subject. Asking a friend/family is something many do. As far as I know the threesome-part is not a common thing; though I can imagine the nice thought :)
Mostly; when you ask another woman to carry your child it is done by combining your own eggcells and your man's semen in the fertility clinic and placing the embryo in the uterus of the surrogate mom. If not only the woman isn't able to cary the child, but it's also impossible to use the woman's eggcells, the surrogate mother can also "donate" an eggcell. Practically this means fertilizing her with the semen of the man. But this usually isn't done by actual sex, but through an artificial procedure of injecting. Sometimes in a clinic, sometimes simply at home. You don't need much to do this; a jar for the man to catch the semen and a hollow syringe for her to inject it in her vagina and you're done :) I hope your friend didn't forget that conception may not be achieved at the first shot; several tries may be needed.
One thing that must be clearly done with a surrogate mother is signing a contract that the baby will be theirs. Also; the rights and duties of the biological mother should be stated. Just like with a sperm donor there is a difference with biological conception. If there is no contract proving it was sperm/eggcell-donation + that the child wasn't conceived biologically, the biological father/mother could be asked to pay for child support. That's the difference between being the conceiver or the donor(&host), technically speaking.
I'm not going to encourage anything "counter truth" here, but just let me add that usually what matters is what's on black-and-white and no-one is going to "check" how the child was really conceived ;) Have her make sure the paperwork is done for all their sakes!
Posted: 30 Sep 20:08