Rissian

Is there a utility out there that can fix conflicting IDs for you? Specifically, I'm looking for one that you can tell to just focus on changing IDs in the config for a single mod. I'm looking to avoid messing up an existing world, and I'm dealing with a self-edited modpack using some kind of ID offset (and I'm unable to discern how much it's offsetting by) that ends up accidentally driving the item IDs into 32000+ territory on a single, newly-introduced mod. Thanks in advance!

Anybody have any idea how updates to custom zips are handled? Would I just need to alter the existing zip so the URL stays the same, or would I have to tell my players use an alternate URL in order to use an updated custom zip?