Can a replenishment plan consider the demand for multiple items and reverse it into one item ?

Hi,

Can a replenishment plan consider the demand for multiple items and reverse it into the planning of only one of these items ?
For example, i have items A B and C and I want to meet the demand for all items through the purchase of item A.

This requirement stems from the fact that our client handles equivalent items but with different purchase prices, so the choice of “preferred” is dictated by having a lower purchase price

What relationships between the items should I implement ?

Regards