I'm sorry I have forgot to reply to your ticket on friday.
I have been trying to figure out a solution yet, that does not involve too much coding, but I couldn't. The current state of the priority code does not work this way.
What I do in this case, is suggest a modification to the actual search code part. That solution would completely ignore all priority settings, and give a higher priority to the given category ID. I don't know if that would solve your problem, because every other priority setting would be ignored. Let me know if that would be ok, and I will put together a modification.Best,
If you like my products, don't forget to rate them on codecanyon :)