How do I add a drum map on only 1 midi track. When I add a new drum map to a midi track the drum grid gets assigned to all the midi tracks. 
  I'd like to edit using the drum grid on 1 track and the piano roll on another track. Thanks

Hi.
First, a drum map is a list of the patches a particular device or software synthesizer uses.
For instance, if you select the Alesis SR-16 Acid Kit drum map, that just gives you the names of the drums and allows you to play those patches through an Aesis SR-16. If you don't have an Alesis SR-16, you'll get the standard General MIDI sounds, not the SR-16's sounds.
If you select a Session Drummer 2 soft synth drum map and don't have that soft synth, you'll hear the standard GM sounds.
What drum map are you wanting to use and do you have the device or synth it's associated with?
 
Do you mean you want to edit the drum track in the drum grid and the piano roll all at the same time? Or 2 different MIDI tracks?
You have to close the drum grid, which is really the Piano roll, in order to open another track's piano roll. If you have drums on track 2 and saxophone on track one and working in track 2's drum grid/piano roll and click track one then the piano roll view icon, since you still have track 2's PRV open, it will open instedd of track 1's PRV.
Close 1 track's view before opening another's.

If I change the output to 'GM Drums (basic kit)' on midi track 1 it also changes the output to midi track 2, 3 and 4 to GM Drums (basic kit), not sure if its supposed to do that.
   I'm using addictive drums on 1 midi track, I'd like to use the drum editor. Midi track 2 I'd like to use the piano roll.
   The only way I get the piano roll back is if I delete the drum map.
    Once I choose a drum map for 1 midi track I can only use the drum grid on every midi track. I get a traffic sign on the piano roll.   Thanks
 
 
 sonar 4 le, windows 7 

Don't know if this helps or not, but you do have access to the Drum Map AND the Piano Roll in the same track - they are simply separated by a divider - just drag it up/down: