[Feature request] Forced replacements

So after testing a bit I noticed that the drops are 100 percent over written. One thing that prevents is that other mods that add drops to other blocks won't be able to drop their own items.

What I would like to have added is a separate config for block replacement that allow other mods to add drops as well.

Basically one high priority replacement and one low priority replacement. The low priority would completely replace drops and the high priority would allow other drops to be added.