There isn't a way, unfortunately. The only options you really have are...A: Create a new painting (be sure save your old one first), and import the images you're going to be using to layers (so each image has it's own layer). Then use the selection tools, and Transform Tool, to move and edit the images to where you'd like them. Export the collage as a png or jpg, then use that image as a tracing image.
B: Import the image as a tracing, and paint the parts you want onto a new layer. Once you have the main areas of paint completed, transform the layer so that it fits onto the rest of your picture, the way you intended it, cleaning everything up by eye/hand.