Hi
As suggested by Ajay Sir, use two different activity types (and thereby two different sec cost elements) for different labur in assembly lines. In your costing sheet, create two base for two assembly line's labour cost and assign sec cost elements meant for each labour cost and then apply OHs (for calculation give from and to line numbers for one type of labour only) it should work.
Kindly test and get back to us with the results.
Regards
Rajneesh








