I can’t seem to assign two customers to one shared checklist (it’s on a single task).
I was only able to assign all the tasks to one customer, and now the other customer whom I didn't assign all the tasks to can’t see the checklist in their compass view.
Any tips or workarounds are welcomed!
Use a participant task? I don’t think they would each have their own checklist, but they can mark themselves done when they have done their part or they have done the list. I am going totally from memory here…. so could be fuzzy. 
You’re correct! The only thing I would add is:
When you use a participant task, the email will only prompt the user to mark their part as DONE. (See screenshot below)
As I recall, when we used participant tasks early on, is the Mark as Complete would mark the entire task complete, and that is not what we wanted. So, yes, we had to be very specific about just marking themselves complete, and not the task. Frankly, it is the reason we decided against participant tasks in most cases.
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