Can we implement a quorum approval in a user task node?

Hello,

As you know, we can define multiple actors in a user task node in a business process. I am wondering to know if we can implement a quorum approval (i.e., M-N approval) in the user task node. In other words, we would like to implement a user task node which ends only when a fixed number of responses are collected.

We implemented a quorum approval by using process variables to keep track the number of responses and a xor gateway which goes back to a user task node when the number of responses does not reach a threshold. A problem is that the actors in the user task node are same. In other words, the same actor can provide multiple approvals. We would like to remove an actor that already responded.

Is there any idea?