Workflow: define billing period alignment
I'm a workflow newbie - and would like to do the following: add a product B to a given subscription. The subscription contains product A, which is invoiced yearly (as is Product B). So far so good.
But: When adding it manually i can chose "Billing Period Alignment" -> "Align to Subscription Start", which ensures that Product B is firstly billed pro rata, then aligned with Product A in the invoice cycle (customer will in year 2 not get 2 invoices but just 1 with both products).
How do i chose/define the "Billing Period Alignment" in workflow?