I don't know how much advise I have but I will share my experience. I have 2 yorkies. One I got as a puppy and the other was rehomed to me when he was 3. I don't know a whole lot about his past situation other than what I was told. He lived with a rotty and grand children were added into the mix. I was told he lived in fear of these young children and that's why she had to sell him. I don't know though. He was awful fearful when I brought him home and cowered and shook a lot. He still will cower some now if I get the broom out and look like he is getting ready to be knocked across the floor. I cringe to think what he has been through--and maybe it's just his personality but I know he didn't get the best care because his teeth were a mess when I got him and she was giving him ice tea to drink when I picked him up--
Anyway, we just took it slow with him but it didn't take long for him to (as my husband says) fall in love with me. If I am in the room he will not take his eyes off of me and will crane his neck to follow me with his sight if somebody else has him. He adores me and I him. In the beginning, he would not play with toys or give kisses. But in time he became like a little puppy and plays all the time with Mayzie or even by himself. I ought to call him Benjamin Button because he was like an old man when I got him. lol He is now 5. He is still not much of a kisser but he will sneak one in everyonce in a while. His confidence has grown alot.
I guess my advice would be to take it slow and be patient with them remembering that their whole world has changed and it will take time for them adjust. I know I have never regretted bringing Mo home....ever!
Oh and Welcome to YT! This is a great place!