Can you add sprites to existing sprite sheet without breaking the tile pallet and in-game tiles

Starting with Default Sprite sheet

Then i want to add a new type of wall (RED)

I can understand why this is happening, New tile assets are not being generated (By design/ bug ?) So pallet gets confused with new sprites. BUT what happens if we re-drag the Spritesheet into the pallet to Generate the new assets and reuse the old once (NOT Overwrite but Reuse) --> well i get a usable pallet again but my Green wall is still messed up. This feels like a bug to me and i need to be sure before i continue, do i need to make a spritesheet 100% complete or is there a way to add stuff later without isolating into its own image and creating / adding to pallets.