This is possible to do. GpsGate Server supports the possibility to include a user in several applications with different rights in each application. This opens up for many possibilities including the one you mention above.
However the only web interface we have to this right now is the possibility to add an administrator to several application, you can however add users in other ways, but it will require direct database access.
Here is how to do it.
First add a Vehicle to one VehicleTracker application. Let's say the Vehicle's username is "dual".
Now you need to open a MySQL shell, so you can write SQL commands directly to the database.
<font face="Courier New">SELECT * FROM applications;</font id="Courier New">
A list of all applications on your server is shown. In the first column application_id is displayed. Remember the application_id for the BuddyTracker application you want to add the vehicle "dual" to. In our example this is 6
Now we should add a group which is linked to the BT application. You do this with this SQL command
<font face="Courier New">INSERT INTO groups (group_name, group_description, bo_type, application_id, created) VALUES('Dual buddy list', 'Some description', 'GpsGate.BuddyTracker.BTBuddyGroup', 6, '2008-03-13 13:29:00');</font id="Courier New">
(Note! Each new group needs a unique name.)
To find out which group_id the new group got, we execute:
<font face="Courier New">SELECT * FROM groups WHERE group_name = 'Dual buddy list';</font id="Courier New">
And we need to find out the user_id for "dual", using this command:
<font face="Courier New">SELECT * FROM users WHERE username = 'dual';</font id="Courier New">
As a final step we should add a link between the user and the new group. We do it like this:
<font face="Courier New">INSERT INTO user_groups (user_id, group_id, group_right_id, admin_right_id) VALUES (7, 13, 2, 1);</font id="Courier New">
Where 7 is the user_id returned in the second select query above.
And 13 is the group_id returned from the first select query above.
Now you can login with user "dual" to BuddyTracker. "dual" will still not be able to login to VehicleTracker since the user only have vehicle rights and not operator rights in VT.
(We will probably add better support for this kind of one user - multiple applications - in coming versions of GpsGate Server).