Hi David,
I read your query several times and i think it will be easy to understand if you separate this into sub questions.
1. You have a Single Sales Organization : US and two common distribution channels.
- why don't you apply the same sales area in the materials so the ordering person will get the clear idea.
2. You have mentioned that as per the partner functions the material exclusion have to be work.
- Currently how are you maintaining partner functions in your system??. Because i think this needs to be work.
Regards,
Nirmal