I have got two sims married and got a baby crib but when I press the 'add baby' button it says the baby needs a family although I have already moved two sims in together.

Okay, I was playing around with it and decided to divorce them... Got the divorce and still had screwed up status. At that point I decided to delete the female ( since the male was further progresses in his job) and created a new character. They have been romantic and seem to be progressing normaly. I will keep you posted, probably not the fix you wanted but its better than a total reset.

Where you by chance switching back n forth between a friends neighborhood and your own? So far I have not visited the party boat while in the middle of two sims being being romantic. So far so good, I'll keep you posted

Stork is en route! It's not a glamorous fix but it worked. Hope this helps!