You can tell the bloodlines of the dogs by looking at the dog`s pedigree.
And as far as AKC UKC registration, AKC doesn`t recognize UKC APBTs as AmStaffs. UKC recognizes AKC Amstaffs as APBTs. Both parents have to be AKC registered as well. I`m pretty sure thats how it goes. Never done this before but read it along the way somewhere. (Correct me if I`m wrong please [=)