I think you are fine with getting weaned kids. BUT, you need to be set up for them.
They definitely need to be in a separate pen for a while and separate stall in the barn. If you give hay, make sure there is plenty of room so they can get to it too. Feed them separately from the big goats too.
We bought 2 new does last spring - first purchases of kids,we have a very small place and we kept them in a pen with our 3 weaned doelings. They went into the barn at night or if the weather was bad <no shelter in that pen except trees>, after the kids were done with 4-H at the end of summer, these new kids were about 8 months old, and we started slowly introducing them to the herd. The goats already 'knew' each other through the fence. Sure, they got picked on a bit, but they learned who they could and couldn't be around, we made sure they had their own area at night all the way up until early this year.
You just have to be prepared to do this stuff. Now, one of those does that we bought is 2nd in command. Her buddy is bottom of the totem pole though, but she's pregnant and just doesn't want to mess with or be around anyone, but then she's our best behaved goat -ever- lol