Rights to manage handheld device objects

Hello,

We have a requirement to provide rights for different administrators to
have rights to only devices associated with particular access points. So
for exanple:

Devices using Access Point A are managed only by admin A
Devices using Access Point B are managed only by admin B
etc.

I tried assigning rights through a query group, by making admin A a trustee
of query group A which contains all devices associated with Access Point A.
But when you drill down to assign an application to a single device in that
group, you don't seem to have rights to. So obviously there is no security
equivelence inherited down to the device level. Is there any way I can
acheive this without assigning trustees to each individual device object?

Thanks,