I have a master assembly.  Within this assembly are multiple parts and Subassemblies.  I want to create a new part within the master assembly.  I use "Insert/Component/New Part".  I then "edit" my new part, and begin my sketch.

All of a sudden, I'm unable to give my new sketch relations with other parts/subassemblies with in this master assembly (example: I want to make one of the lines of my new sketch co-liner with the edge of another existing part).

I swear I've been able to do this in the past (use relations with new parts and existing parts/subassemblies).

Question:  Is there a setting or something I accidently turned on/off, or have I never been able to use this method and am just now realizing it?