stool request

Can anyone make a stool that does the following:

  • I make a car, add a seat and wheels that uses 8 to move. then I make a tank with a seat and cannon that uses 8 to move it up. with the STOOL I just click on the car and when I sit on the car seat and press 8, the car moves but the tank doesnt rise the cannon. I click on the tank with the STOOL and when I press 5, the tank fires but the car doesnt do reverse. Possible?