Before I start banging my head against the wall trying to see if this is passable, I thought I'd ask the exports. Is it possible to substitute a block for another block inside an anonymous/dynamic block? For example, you have a master dynamic block that has left & right end caps. The end caps could be any combination of sub-blocks A, B, or C. Can I loop through the anonymous block, find the place holder for the end cap block & substitute it for the new sub-block without screwing up the other master blocks with the same definition?