Anvil Enchanting Rework

Please add it so that if you have an armor piece, let’s say a chestplate, with Fire Protection 4 you can combine it with a Protection 4 book and it overrides the fire protection on it. Additionally, let’s say you have protection 4 on your chest plate and you want to combine it with a fire protection 4, unbreaking 3 book, instead of it being completely impossible to add, make it so that if I put the book first then the chest plate the protection enchantment doesn’t get overridden but if i put the chest plate first then the protection gets overridden with the one on the book.