RMT has called strikes of drivers on the Picc and Hammersmith and City Lines for 6-7 December. They're facing similar issues - management abuse of procedures, arbitrary and authoritarian discipline, and, on the Picc in particular, victimisation of union reps.
All drivers, whichever union they're in, should participate in the strikes.
RMT stations reps are meeting on Monday 28 November to discuss their dispute; they should push the union to name strikes on stations to coordinate with the drivers.
These strikes also happen to match up with the next walkouts in the Southern guards dispute - a significant added bonus!