If you right click on an entry, you get an option to add new material, then fill out all the relevant spec you want for that.....else, just select copy & paste it to the folder you want, then rename it accordingly.
FYI: fast way to get to Material Table...."double click" the Material listing in the Pathfinder. [if you don't already have the "Prompt for material...." checked in SE-Options]
I do hope developement update the material table dialogue, to be able to reorder the material listings, on the fly.....without the need to modify it externally in Excel.
Sean Cresswell Design Manager Streetscape Ltd Solid Edge 2019 [MP1] Classic [x3 seats] Windows 10 - Quadro P2000