Any suggestion on this? More than 1 year without response...

It is not possible to use By-products with Project Deliverables. Please feel free to request this using the Idea section of the community. Remember to describe the requirements and scenario in which this is relevant clearly. 

As I understand to the Project Deliverables and Your answer, By-Products can be considered under the decoupling point, when the supplies are created by (P)MRP according the valid product structure where the By-Product can be attached. On the contrary, there is no option to design By-Product above the decoupling point directly in the Project Deliverables structure where the supplies are pegged. Of course, there is still option to add the specific By-Product manually on the level of the Shop Order as the pegged supply.

Am I right?

Thanks in advance.

Best regards,
Zdenek Baumelt

By-Products are supported by MRP, and you can always manually add a By-Product to the shop order once created.