I agree with Oddsock:
Move the puppy's xpen far away from your dogs' piddle pad.
Relative to relations between the puppy and the older dogs, let them work it out on their own -- unless things look dangerous.
Greet, pet, and do everything for the older dogs first. Keep their routine as normal as possible and lavish them with the same praise/affection that the puppy is getting.
Training helped bring my two boys together. Doing simple tricks for treats. We also played fetch and walked together. You will have to wait on the walking until the pup is old enough.
I also agree that you should try to talk to your SIL about giving pets as gifts. Tell her that you appreciate where her heart was, but pets are a big responsibility financially and in terms of time. Not everyone is prepared for this responsibility. Also, where they come from is important.
__________________ Kristin, Max and Teddy |