Rather than kill anyone, take them prisoner. Sell them to the Lannisters and let them do the killing.
By not killing “anyone” you aren’t including the troops outside, are you?
I just to keep it front and center that the RW included more than just killing a few people dinner ala Tywin.
Well, the challenge was to describe a “reasonable” alternative. I don’t think killing the troops outside was necessary – the Boltons and Freys had them outnumbered, and we have plenty of examples of armies being effectively controlled through the holding hostage of their liege lords (see the Karstarks in TWOW).