It’s a good idea to socialize pittys with all types of dogs and people. If the dog you currently have is trained there should be no issues. Let them meet and get to know each other, but don’t let any aggressive behavior start from either dog. Your dad may know what that looks like.
For multiple dog families, it’s usually easier if the dogs are of the opposite sex. It may also help if one is older. If the one you have has been in the house a while, he/she can actually help “train” the new pup.