Projecting Pharmacy/Healthcare Payable

Hello Monkeys,

Working on building out a CVS DCF, and have become stuck on projecting the Pharmacy Payable line item and Healthcare Payable. I projected AP as COGS days, would I do the same for these two? I have Benefits Cost line item as separate from COGS, so I was thinking of linking Healthcare Payable to Benefits Cost, and Pharmacy payable as a % of Services Revenue but idk.
Thoughts?
Still an undergrad*