Can anyone help me out with the name of the file that keeps the approved Manufacturers and their part numbers?

Nope, its is BKSBMFG.B  
 
 
[BTW, here is what I did to find it: open IN-B, bring up an item, add an entry under "Mfgrs" (manufacturers), then open the DBAMFG (or EVOERP) folder on the server, go into company files folder, sort by date modified (descending) and look at the files that have been modified in the past few minutes. Only one of them had the letters "MFG" in the name. Then I opened that table with Maintain Database to see if my entry was in there. Ta da!]

That's it.  Thanks