I am lost.
Whose watermark must be on there? The copyright holder's?
Do you have license to the pics?
Who took them? You or the other guy?
Let me see if I can change the names and understand your situation.
My mother has a website
www.baddogsmom.com
You have a fan site devoted to my mom, and you are using pics you bought of my mom
My mom says she wants
www.baddogsmom.com watermarked on the pics or you must remove them.
Is that accurate? Or did you get the pics off newsgroups and you do not have license to use them?