FTL/Instructing
Skipname.
Have a word with your Fleet Manager first and discuss it.
Some airlines don’t mind p/t. instructing provided it doesn't interfere with your main job.
Later, some might even consider your instructional experience when you apply for a Training post.
I did it with permission but the hours weren’t included in the Airline cap.
Sufficient rest is the key factor. Perhaps you won’t feel like it after a heavy Summer and/or you’ve got a family ?
Maybe just fly enough instructional hours to maintain your F.I Rating ?