Have you alerted the owners about the hip dysplasia in case they decide to have another litter? My heart sinks when such young babies are cursed with something hereditary before they have a chance to grow up. It's not fair.
Our boy Brody was recently diagnosed with hip dysplasia, he's almost 4yrs old and 57lbs. He is currently on Previcox for an anti-inflammatory, but after a week of getting it he is still favoring his worst leg. Have you discussed putting Gumdrop on supplements? We have Brody on an Osteosupport brand, you'll want to find something with glucosamine, chondroitin, omegas, and green lipped mussel. There are also supplemented mobility support diets available, but I think most are for dogs 1yr or older and wouldn't support a growing puppy properly. You can also get orthopedic pet beds with memory foam to keep her comfortable.
We are looking into doing a total hip replacement for Brody because his size makes it possible. I have seen a few FHOs done on med size dogs before and they do quite well. There are clinics that are willing to do small dog THRs, but I can't remember the names. If you search on google they will pop up.
Good luck with your pup! I'm glad she found such a loving home willing to go above and beyond to keep her happy and healthy