WQS 10.2 FRACAS: Calculations for Subtable evaluation

I´d like to evaluate the responsible for the next action in a subtable with several records and transfer this person to the problem table as "next action responsible".

Criteria: Task in subtable not "Done", next or minimum Due date, if two or more tasks have the sam due date take the one with the lowest ID.

I already could calculate the next or relevant due date, but can´t filter the person that correspons to the relevant next due date.

Ideas? Solutions?