i think it's great that you & ur hub hv found this woman. plus, she's a package deal, which can make it even better.
if she needs a place to stay, until she gets on her feet, i don't see the harm in helping her out. as long as she doesn't take advantage of you guys.
as for moving in, there's a lot to consider, finances, her daughter, how ur family & friends will react.
nothing is set in stone either. if you try and it's successful, awesome. expect some bumps along the way. if it doesn't work out, she cd always move out & u guys could still have a relationship.
best of luck to you sweetie.