How does billing work for Projects?
Billing is shared between all Projects. Simply set-up billing for one Project, and all other Projects will share that billing and same bucket of survey volume per month.
For example, if you had 3 Projects and 10k surveys per month, that means you have 10k surveys to use across those 3 Projects for any given month. You might divide up 5k for one Project, and then split the remainder for the other Projects. Feel free to distribute as you'd like!