You made the usual assumption that "mini rose" means the plant stays small. That is not true. "Mini" only applies to the size of the bloom and the leaf. Miniature rose plants can and will get as large as regular size roses if they are happy. And there are miniature climbers that will grow to 12 feet tall and/or wide.

I would leave well enough alone on the bigger pots. In fact I would suggest you put the new ones in bigger pots. The ones in the 14" pots will need to be root pruned annually to keep them happy in those smaller pots. If not they'll eventually start to fail because they are root bound. If you really want to keep the others smaller, cut them deeper when you deadhead the spent blooms. You can cut them by 1/3 to 1/2 their height at that time without doing damage. However, if you are experiencing this awful heat wave and drought I would suggest waiting until things cool down before doing anything to them. They're probably already stressed and any further shock could do them in.