Dilbert,
What I do when I went to satisfy my liege but don't really want to have my troops under his control, is that I accept to give him the troops, but send no money to support them. The regiments quickly shrink, until they just vanish and reappear in their original provinces.
But beware:
- Even if they did not fight, you have then no regiments available since all soldiers died of hunger so to say. You will not be able to wage a war for quite some time.
- As soon as they reappear in their province, weakened (just a few hundreds, sometimes less), the liege will send again a request to mobilize them, which is ridiculous.

Lieges should wait for the regiments to replenish, let's say, at least to 33%, before to send them to the battle. Do not know if this is doable in the scope of [...].
- The nobles leading the phantom regiments under your liege's command, and your ruler first of all, may get serious problems when fighting real armies: get prisonneer, wounded, etc.
So... not a miracle solution, but a trick you may want to use sometimes, especially in your case where no real fight is happening.