How do you center a part between two parts?

I have two bearing rails on either side of a drill chuck.

Ordinarily, in my previous program, I would construct a line between the two outer parts, then move the inner part by selecting on it's center, and moving to the midpoint of the line I constructed, with a filter allowing it to only move in the plane I choose.

But with Creo, I cannot even snap on a part that isn't active. So in order to even draw the line between the two outer parts, I have to activate one, put a workplane on it, draw a point in the corner; go over to the other outer part, activate it, then draw a line between the active part, and the point I drew. Then I can snap to that midpoint, and move my part. Is this really how it's done, or is there some easier way?

Also, is there a way to snap to parts that aren't activated? Some commands do, some don't. And it seems the commands where I need it, it isn't there, and vice versa.

I have to add that I'm getting addicted to this program. It's a lot of fun when I know the in's and out's.

Thanks.

Gregg