Amanda....introduce them outside of your house. It is neutral territory. It doesn't have to be away from your house...the backyard is fine.
In the beginning make sure Ranger understands he has not be replaced. He gets fed first, he gets greeted first, first treat etc. This will always not be necessary just in the beginning.
With the two so young and close in age...I'm thinking you'll have no problem whatsoever with adjusting.
Congratulations on Ryder. He's a cutie.
I'm sure Nicki is glad he's getting a home from a fellow yt'er.