Will my pup play nicely with a super tiny Yorkie pup?

My sister in Law has two Yorkshire Terriers one is an adult the other is 2 and half months old puppy(very slight of frame, maybe 700 grams). The adult runs from Bixby when he tries to engage in play, but he hasn't had any contact with the puppy. In two weeks my wife and I will be spending a weekend out of town, my sister in law will be puppy sitting at her place. My question is two fold, 1. Will she need to constantly keep Bixby and the the Yorkie pup separated? 2. Would Bixby hurt the little Yorkie if he got a hold of her and tried to play with her (i.e. should i look for another sitter)?

Thanks
-R.

sister in Law will have to keep them apart while she not there and keep a extra eye on them make sure nothing will go over the top

Introduced correctly you shouldnt have a problem but as steve says keep a very close eye on them. I have friends wth cats, rabbits, chinchillas living happily with staffies but remember a playfull rag could be the difference between life and death. i wouldnt trust either of my two with anything less than 5kg bigger than them unattended

Agree they will have to be kept apart if not supervised. One of Suki's best friend is a Corgi and she tailors her level of play to his size. It really all depends on the dog as well and how well it is socialized.

Let me add that Bixby (my staffy) is just three months old, so he's on "super play mode, level 10" quite often.

I agree with what everyone else says, make sure she doesn't leave them unattended, I'm sure Bixby wouldn't mean to hurt the little yorkie pup but that doesn't mean he won't. It might be easier for your peace of mind to find someone else.

Update: Bixby had a peaceful visit. His few supervised interactions with Petite were marked by sweetness and gentleness on the part of Bixby. And apparently he was super calm and well behaved. On another note, he's been an uncontrollable ball of energy since he's been back with us.