I'm not quite sure how possums are beneficial, however for the coons, if you really want to get rid of them the only way is to poison them with a high velocity lead pill of some sort. A friend tried the relocating method and the coons had found their way back in about two weeks. I guess if you drove for about two hours on an interstate highway it might give you a few years before they found their way back, or got run over on same said interstate. By the way, depending upon their diet, coon can be pretty tasty if prepared right.