If you've read through the Surface Automation documentation, then I'm not going to go into detail here. But you may have missed the info about padding which can be used as the sort of alternate search location for images. I don't have the docs or BP pulled up right now so my wording may be off. But basically if you wanted to, you could set the padding for a region to encompass the entire screen. And then BP would first try to find the image in the middle of the defined element location and then would spiral outward looking for it. This is as opposed to as you suggested where it could instead be tied to a parent image.
Also, I'm referring to BP 6 so if you're in BP 5, I'd suggest going on strike until your organization meets your demands of upgrading. =)
Dave Morris, 3Ci at Southern Company