Yeah the issue with this approach is that I have over 25k products. This would bring me with over 50k products, something that is simply not acceptable for various reasons.

The approach with this subcontractor is that there is no PO generated. Rather we get multiple products from different clients and we combine them in the same batch and simply ship it off with a detailed list inside the box.

These are MTO products. Is there a way to add multiple routings? One with coating and one without?

If not, this might be a dealbreaker for buying the solution. :(

@cybrosys I have already read that link and watched the video. Unfortunately that approach would apply to all my products. This is not the viable. Sometimes we might need to send the product to the subcontractor and other times we wouldn't. We would need a solution where we could apply a subcontractor rout on the sales order opening stage. 

The product you receive form the customer must be "Non Grinded" and a component in the bOM for the finish product.

For scenario 2, you would need a sub product "Non coated" that you send to your subcontractor, and you receive the finished product.

It is possible to hav two alternative bom, but the description I have read, is not very efficient.  

You must register 3 bom, and the first one (that will automatic be selected when you create a manufacturing order) should have no components.   Then the manufacturing order will not be automatic confirmed, and you can select which BOM to use.  So very manual.

I would have selected the option to have two different products. One with subcontracting and one without.  Faster and easier registration.