There should be an option to import vanilla loot tables

When I am making a loot table for pre existing minecraft features, (names I get from here Minecraft vanilla loot tables list | MCreator) I am then overwriting the pre-existing vanilla loot, I can recreate this but this is hard and time consuming to do, as you see here, the tables are complex: Desert pyramid – Official Minecraft Wiki (fandom.com). So what I would like is a way to import these existing tables and edit them to just add my own, or maybe even a simple option to add things to loot tables as I imagine that the current system probably can create conflicts with multiple mods trying to override the same chest.