Stiching a file (end screen) as a template?

So, looking at the stitch capabilities in media encoder, and have successfully stitched two videos together in the program, but was looking at saving presets and incorporating stitching, and don't see the option and my searches have been in vain.

Basically, I'm making videos that need to go to facebook and youtube.  I want to just edit one timeline, but then send to media encoder and kick out a facebook version and a youtube version that will append (stich) on the endcard for the subscribe and related video overlay  endcard stuff youtube does. 

Is this possible?  If I'm not clear, please tell me and I'll try to rephrase.