I have a small business drawing architectural plans for contractors and individual owners. My field is very small so I know most of the people, contractors and owners in it. I give contractors a cheaper rate as they give me more work.

This week I come to find out that one of my biggest clients is whiting out my information from my plans and selling them to other contractors for whom he isn’t doing the work for saying he is an architect at triple what I charged him. 

I’m not sure what to do about this as I don’t want to lose him as a client (the two times I found out this week I spoke directly to the person he sold them to so I am sure they will go directly to me in the future). Should I confront him? Or go around him maybe find out who is doing the job and contact them every time to let them know what he is doing and to just use me? I don’t believe he is breaking any laws as he did pay me for the work and technically isn’t duplicating the plans, just not using them for himself.