How can the Company segment be derived for the correct Sold To Legal Entity?

Summary:

Currently, our client uses one management business unit across multiple legal entities. When an LE, that is not the default for that BU, is used on the PO as the Sold To Legal Entity, we want to configure SLA rules on the PO Charge Account Distribution to derive the segment 1 (Company) value based on the relevant legal entity.

Content (required):

We are currently sourcing this value from the inventory organization. However, I would like to understand if there are other options, as some countries have dozens of legal entities under a single BU, which means means we may need to create an equivalent number of inventory orgs.