One discount code per affiliate
It is advised to set up a different fixed Shopify discount code for each affiliate.
This helps accomplish two goals:
Performance of each affiliate can be tracked separately
Each (tier of) affiliate(s) can be provided with different discount levels
One promotion per affiliate
We advise you set up one promotion per affiliate, each coupled with a different fixed discount code.
This allows you to configure each promotion with different copy and a different look & feel if required.