I have a 3 year old mini-aussie (all of 10 pounds) male, he's anti-social with most other people and other dogs (loves our cats though), despite training classes, agility, and other efforts to socialize. He's just afraid of everything. But he's typical aussie in all other ways.
My husband always wanted a samoyed, when we had an unexpected chance to help a samoyed puppy, Ozzie was here. First weeks, Ozzie was sick and under quarantine. Woody would look into the area where Ozz was and growl a little. When they finally got to meet, it wasn't pretty at first, Woody was not too happy with this giant puppy in his space, but within a week they were playing tug of war with a sock. Woody's MUCH better around other animals now, too.
Most of the people here have much more experience than me, but
I think that most dogs, and yours sounds like a lovely dog, adapt to the new addition relatively quickly. Of course the new dog's attitude is important. Ozzie is very sweet and friendly (too friendly, sometimes) and I think we would have had major issues if he'd of been an old grump like Woody can be. We weren't planning to add another dog, due to Woody's attitude, but everything worked out fine with only rainy day hiccups.
This is from the first day of the two meeting, you can just see Woody's immense pleasure at the event.