iStockphoto: Multiple Model Releases
A question that comes up periodically among new contributors to iStockphoto is “how do I attach multiple model releases to my upload?”
It’s a good question, as there is only one upload box in the interface for attaching a model release. If you upload one release using that box, then try a second, it’s only the second that gets attached.
The solution is pretty simple: Just combine your releases into a single JPG document, and upload that. Your model releases 
should already be JPGs; just open a new photoshop document large enough to accommodate your two (or three or four) releases, and paste them into it. I like to do mine side by side, I see lots of folks stack them vertically into a single long document. Once, when I had five or six releases all in one document, I went one step further: I tiled them into a document 3 releases wide by two releases high, and included a reference key indicating which release went with which model. It’s not required, of course, but that little step certainly can make things nice for the inspectors.