The short answer to get hoof walls to stop chipping in the majority of cases is to keep a mustang roll on the hoof. And maintain this roll consistently. I check hooves before every ride with rasp in hand looking for areas that could use attention.
The long answer is to learn barefoot trimming and elpo hoof mapping.
I see that you were saying that the front was chipping under the shoe...... I don't know what would need to be done in this situation. But on the unshod hinds.....keep the walls rolled.