This tool merges grouped meshes in a level together with the unreal merge capabilities in bulk.
The merging process saves data on the original meshes when merging a mesh so that the merged mesh can be reverted and adjusted before merging again.
(This is all made in blueprints for Unreal Engine 5.1, 5.2 & 5.3 and can be found on the epic marketplace.)
https://www.unrealengine.com/marketplace/en-US/product/bulk-static-mesh-merge-tool