Sometimes you have to find a solution that isn’t the one that immediately comes to you. Why not relate gallery entries/images directly with the weblog entries? You can definitely do that using related entries.
I haven’t found an ideal way to deal with images and the CP. A site I built for a client relied on them editing/managing via the weblog entries, but adding new entries was done only through the front end that I built for them - same interface as for their users.