Predecessors for parallel activities

I have a situation where a task happens in parallel with other tasks but this parallel activity (call it "Task P") needs to start at the same time as "Task A" however "Task P" runs longer than "Task A" but needs to be completed 2months prior to the completion of "Task B"

So I want the Start Date for "Task P" to be linked to the start of "Task A" <-- which I know I can just use the Start-Start predecessor.

But I want the Finish date for "Task P" to be linked to the finish date of "Task B" with a 2 month lag.

I can't figure out how to use predecessors to provide both a start and finish date