The BOM is tricky because components will be added to existing BOMs even if you copy the files and do the other tricks that have been suggested for ither files such as Inventory.  If you are making a LOT of changes, I suggest exporting the BKBMMSTR file, clean up the file in Excel, then Initialize the BKBMMSTR file to delete all BOMs and then import back in the new data to the temporary file, run an error report and then transfer.

I have been using an SQL insert to load thousand of new BOM dynamically.  I use VB to read excel or access data and create an GetBOM.sql files that I open and run in pervasive.  
 
This is a sample of one I just ran.
 
INSERT INTO "BKBMMSTR" ("BKBM_PARENT", "BKBM_PROD_LINE^", "BKBM_COMPONENT", "BKBM_QTY_REQD", "BKBM_PROD_TYPE", "BKBM_PROD_SCRAP", "BKBM_PROD_OP", "BKBM_PROD_PRICE") VALUES ('207-2226-001/2',5,'FIT221V-1/4-0',0.2,'R',5,'  0',0)#
INSERT INTO "BKBMMSTR" ("BKBM_PARENT", "BKBM_PROD_LINE^", "BKBM_COMPONENT", "BKBM_QTY_REQD", "BKBM_PROD_TYPE", "BKBM_PROD_SCRAP", "BKBM_PROD_OP", "BKBM_PROD_PRICE") VALUES ('207-2226-001/2',6,'0431164281',1,'R',5,'  0',0)#
INSERT INTO "BKBMMSTR" ("BKBM_PARENT", "BKBM_PROD_LINE^", "BKBM_COMPONENT", "BKBM_QTY_REQD", "BKBM_PROD_TYPE", "BKBM_PROD_SCRAP", "BKBM_PROD_OP", "BKBM_PROD_PRICE") VALUES ('207-2226-001/2',7,'WIT-18SF',1,'R',5,'  0',0)#
INSERT INTO "BKBMMSTR" ("BKBM_PARENT", "BKBM_PROD_LINE^", "BKBM_COMPONENT", "BKBM_QTY_REQD", "BKBM_PROD_TYPE", "BKBM_PROD_SCRAP", "BKBM_PROD_OP", "BKBM_PROD_PRICE") VALUES ('207-2226-001/2',8,'50-57-9011',1,'R',0,'  0',0)#
INSERT INTO "BKBMMSTR" ("BKBM_PARENT", "BKBM_PROD_LINE^", "BKBM_COMPONENT", "BKBM_QTY_REQD", "BKBM_PROD_TYPE", "BKBM_PROD_SCRAP", "BKBM_PROD_OP", "BKBM_PROD_PRICE") VALUES ('207-2226-001/2',9,'16-02-0087',14,'R',0,'  0',0)#
INSERT INTO "BKBMMSTR" ("BKBM_PARENT", "BKBM_PROD_LINE^", "BKBM_COMPONENT", "BKBM_QTY_REQD", "BKBM_PROD_TYPE", "BKBM_PROD_SCRAP", "BKBM_PROD_OP", "BKBM_PROD_PRICE") VALUES ('207-2226-001/2',10,'641994-1',1,'R',10,'  0',0)#

Quote from Lynn_Pantic on 06/27/07 at 16:09:48:

Speaking of validation, I find it strange that the import program does not allow 0 quantities, but you can enter 0 in BM-A.
 
I have two reasons for 0 on BOMs. We use routings only for costing/estimating, and a LABOR item only for recording. So we don't want a LABOR amount on the BOM or it will be added to the cost, but we want the LABOR Item on the BOM so that we have a place ready to record it.
 
The other reason is for substitute/alternate parts. We have the normal part with normal quantity, but want the sub/alt part listed so we know what it is and have a place to record it on the traveler if used.
 
 So I usually just put in .00000001. So far we haven't done an order that is affected by that number....