Instead of running in parallel, how about cycling through handling only once servo at a time. Well, actually, you can do about 8 servo's like this if all are at the 2.5 ms extreem. You would need to do two timers to handle 12 servos.

But it would work like this...
a) Select the servo to service.
b) Calculate the time delay needed,
c) Turn on the servo signal
d) Program the timer to interrupt when the servo signal should be turned off.

The interrupt routine looks like this..
a) Turn off the selected servo signal.
b) Select the next servo
c) calculate the timer delay for the servo and program the timer.
d) turn on the selected servo
e) exit.

As said earlier, 12 servos would need two interrupts. Hopefully the interrupts won't be too long to affect the accuracy of the servos on the alternate timer.

<>< Lance.