I think what the other posters meant Karen was that the baby / toddler could get caught in the crossfire if a fight between the dogs happened. The baby when it's older toddling along perhaps with one of the dogs (as they do) and the more agressive dog goes for the dog that the toddler is next to and accidently hurting the toddler, rather than the dog going for the baby / toddler.

If feel for you and your fiance as you obviously want what is best for the dogs. Is the more agressive dog used to other dogs being around?