Multi Instance Pool Coordination

Hi everyone,
I wanted to know if this way of proceeding is correct or not.
Specifically the main process must execute the “Add” activity if 1 day has passed or it must execute the “Remove” activity when the FIRST message from all members is received. In both cases the process must terminate. The “Remove” activity must be executed only once, when the first message arrives.
I don’t know if this is the correct way to proceed in the presence of a multi instance pool. Could anyone point me to an alternative way to proceed?