I was in the same situation not too long ago too (minus the puppy part). Kai seemed to not care for Kaedyn then started looking a bit sad and wouldn't do was he usually did around the house. You need to give them alone time. They need time to bond also but alone time is just as important. We seperated them for a few days. One would be upstairs with my mom and one would be downstairs with me. Then I'd give them some time together through out the day. Just take it slow. Kai has started warming up to Kaedyn and has actually wanted to play with him.