At the park or anywhere the puppy can pick up and catch all kinds of things.They have some immunuties from the mother but not knowing the situation the pup may have been taken to early and not been given all the immunities and lots canbe passed through stools and even the grass, let alone contact with other dogs.I would wait until the dog is a bit older and has it's vacinations.I do like the newer vaccine protocals.I think we do tend to overvaccinate but I do think we need to still do it just not as much and some other changes(whole other topic-controversy) but to keep the puppy safe I would not expose it at such a young age to dogs with who knows qhat.You can socialize it with dogs that you know are heathy and vaccinated.She should check with her vet but if her dogs are vaccinated and the puppy has been checked she is probably ok.What I would think she would have to worry about are things like worms,kennel cough,parasites of any kind ,fleas.I hope things work out.I m a firm believer in rescues.I do it myself..
Laurie=Byakko's Mom