Just for conversational sake...

... I notice on your original clump that the "stickers" are very much prominent.
I always go thru my quince and cut them off before working on them. Just a suggestion, but you might consider that as a routine. Saves the hands from being bloodied and makes it easier to work on including wiring.
One of the nice things about quince is that you can use a method of partial wiring and clip and grow. Once your happy with your basic movement it is very easy to keep with them with the clip and grow method.
I think one of the basic "foo-bahs" with initial quince design is that it's easy to get clip happy
and you can really reduce the following year's color display. I usualy allow the new growth to harden off before pruning and then I go down to the base of the new growth and clip at the second or third leaf cluster. I determine which one by the direction the main leaf is pointing because at that junction the new growth is apt to take off in.
Keep us in photos pls