How do I make Single Manufacturing Order for Multipal Finished Products?

We are manufacturer of Engineering Goods - Product A

BOM for Product A is (Part a - 1 No. + Part b - 1 No. + Part c - 1 No.)

"Part - a" is made from (Raw Material 1 - 1 No. + Raw Material 2 - 2 Nos.)

"Part - b" is made from (Raw Material x - 1 No. + Raw Material y - 1 No.)

"Part - c" is made from (Raw Material 5 - 1 No. + Raw Material z - 2 Nos.)

Now we have got an order from our Customer for "Part a" - 2 Nos and "Part b" - 3 Nos.

How do i make Single Manufacturing Order for both this product by selecting Part a and Part b as Finished Product ?

The Main reason behind asking this question is, our Product contains 40 Parts while manufacturing.

After supplying said product, we are getting orders of Spares for the said product time to time and we have to issue single Manufacturing Order for that to our production department.