Hi Srinu
If you have defined a new condition table with material number, then why the Step 4??
If you wanna use the overhead key, then you don't need a condition table. You can use standard sap feature of overhead group/overhead key
If I were you, I won't even go for costing sheet. I would either add an activity type in the routing, activity qty would
be the cost you wanna add and activity price will be 1, activity UOM will be EA.
Another option add a dummy material in the BOM, qty of the material will be the cost you wanna see and planed price of this material will be 1.
Br. Ajay M