Hi,
One BOM is enough as you structured above.
About Strategy Group:
I worked long back with this. So i request you test what i saw.
After maintaining Strategy Group for X1 and When you create Sales Order you will have options in Requirement Type, there select MTO and Save.
Rest of thing is as normal.
Try whatever we discussed till now in a Developement server, you can understand it. During execution if you have any issues let we know.
Thanks With Regards,
Dinesh V.