In the SAP ECC there is the functionality to have the supplier and customer material number and description linked to your internal material (in the reg info). The SAP by Design doesn't have the same functionality to link your material number and description with your supplier?
One example of the Reg Info in the SAP ECC
How To Create A Purchase Info Record
For the sales point of view:
All About Material Exclusion & Inclusion (Listing)
and
Text determination for sales document header / item
There is not this functionality in the SAP By Design ?