You said his parents took care of them so do you live with his parents? If not then have you talked about his parents maybe taking the cats? Pet's are not disposable so you need to either rehome (not rake them to a shelter) or find away to live with them.
You could try brushing them daily and using a damp wash cloth on them to remove as much lose fur and dander as possible. Some cats will tolerate a bath but I wouldn't force it on a 12 yr old cat. Create cat free area's in your home. We have 2 cars and even with no allergies we still keep them out of our bedrooms. Not many people like a furry pillow. If you really try everything to coexist with the cat's and it's still not working then your husband may be more willing to work with you but from the little info you gave it sounds like you have a few options to try still.
Keep the cats out of the baby's room entirely, so the baby has a place to sleep where there has been no cat dander. As for you, try Claritin or Zyrtec. I think you should have discussed this before you got married -- not fair to cause a scene years into the relationship. Suck it up and deal with the cats. In your shoes I would just get allergy shots and go on with my life.
I'm allergic to cats. I have two cats. I developed an immunity to them just like my dad did to his cat. Eventually, you and your daughter will too.
I've been involved in pet rescue for 7 years. I think it's really sad you are insisting on getting rid of two cats your husband has had for 12 years, no matter who cared for them. You're giving them a death sentence. 12 year old cats are rarely adopted.