Ok. This is a subject that you may have to be carefull about. There are a lot of 'Fake' images of famous people on the web that have their heads pasted onto nude bodies. If these are people that you personally know I would definitely ask permission first. Unless you are actually going to digitally paint the topless part of the image, then you are going to need photos of bodies. This is the same problem as above. You need to have original photos of bodies that you have photographed and the permission to mix and match them from both models. Would it not be easier to take the photo's topless in the first place though? LOL...