I was having the same problem, crashing at the intro.  I restarted my computer and it has worked great since.

Now that he is pregnant and has an invisible body, the game hangs every time I try to edit him for clothing.  Pregnancy won't last long so I'm not real worried about it.  A new mesh would be nice though.

It was interesting with the surrogate for my other child.  I created her with the traits I wanted for the combination, and moved her in to the two married men's house.  When she gave birth, one man was listed as the father and the other the stepfather.  I like the way they thought that one out.

BTW, I don't see much by the way of natural in this game, considering life fruit, death fish, plant sims, vampires, and cars that disappear into your pocket

I've been searching and trying to use every trick in the book to force a male pregnancy for my gay male couple.  Deleted females from the town and played other families hoping the game would just generate a child for them. To no avail.

They had already adopted and but they also used a surrogate and the baby only had one father's traits.  They wanted a child of their own, and one of them kept having the wish to have a baby and have a first child.

After I installed awesomemod I figured out that I could pull up the cas (cheat code entry) and type in editsim.  I was able to switch one male's gender to a female just long enough to try for a baby and they got pregnant immediately. I then switched him back to a male and he is now pregnant and with the invisible body of course.

Anyway, just wanted to thank the creator of awesomemod! It was driving me crazy.