No connection between then except that it sounds as if the brushes are worn out on both motors and making intermittant contact, or that the switches are bad.
If the console switch for the rear window is bad, the door switch won't work either, there is no connection through the switch. New one are something like $18, and you are going to need one someday anyway. All the same.
The switch for the sunroof could be bad, too -- eventually it will fail and you will have to wind it shut by hand (motor is behind the cover in the left rear).
I've also heard of wires coming unscrewed in the fuse box, for that matter. Would affect left front/right rear window, though (on one fuse).
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!