Need more replacement options when deleting assets

I wasted a whole lot of time adding a small set of materials to a very large set of meshes. I thought (I should have verified) I’d just be able to replace the material references with material instances of another material. Right now I get to waste a couple hours reapplying material instances to each mesh before I can delete the old materials.

Oh yes, I hate that. It seems so unlogical to me why I can’t just replace the material reference with another material I have.

Yes! +1 THIS! I have imported tons of meshes into my UE4 project, I have a new material instance ready to apply so I delete the older default material and it pops up reference replacement window but in the drop down my instanced material does not show up! Only base materials show up.
Which is weird because if I were to open any static mesh from content browser by double clicking it, I can manually change its material to my material instance. But this functionality is not visible when using replace references tool.

PLEASE HELP! Manually going in each static mesh and assigning my new material instance will take forever!