Right click
then click save to file
.
It'll save art of that part to file. It'll have size of this albedo.
Right click
then click load from file
.
It'll load an art to this part, exchanging old one to this one. Old mesh will be inherited.
Right click
then click make emissive
.
It'll create an emissive with same art as albedo.
You can check emissive working by enabling post processing.