Currently Relay does not support "either/or" approvers.
We have use cases where we have multiple approvers in a process but only need a certain amount of approvers to continue the workflow. i.e. There are 3 approvers in a process but we only need 2 out of the 3 to approve.
Adminschang (Product Manager, Box) commented
Users now have a way to assign a task that requires only 1 of a group to complete.