Hey guys,
I tried to search for an answer, but didn't find any. My main question: Are there some stock agencies that give you disclosure regarding who bought a license of your photo?

My situation is this: Right now I sell my photos only over my own Photoshelter account on a RM licensing model. To reach a bigger market, I would love to sell over a different stock agency.

However, due to many copyright infringements, a decent part of my revenue comes from those. This means, at any point I need to know who has the right to use my photographs and who doesn't. Also, I need to keep the right to go after these infringements, not give it away to the stock agency.

Is there some agency that offers this disclosure? Or do you really always have to guess if your photo was stolen or purchased?