Leak in pool plumbing, questions and advice please

Been in the house for 20 years, and periodically have had to patch up small cracks around the skimmers as settling ground pulls them away from the Gunite.

It's been a few years since the last time, and now I can't remember what product I previously used. A couple of weeks ago I tried it with aqua JB Weld, but it is crumbling and pulling away.

First questions, what is the best product for those small cracks? Is draining the pool below the level of the skimmers necessary, or is the product applyable underwater?

Also, doing some pressure testing today by closing off one or the other drain at the bottom of each skimmer, I am able to draw air into the system from Below one of my skimmers, so I know the pipe running from that skimmer to the pump must have a crack.

This is consistent with my understanding of how this usually goes, as the ground settles, but skimmer is largely fixed to the pool, the pipe is pulled away and cracks, almost always very near the skimmer.

Will this require removal of my concrete deck in that area for Access and repair? Is there such a thing as an internal patch, especially if on fiber optic inspection there is not significant pipe displacement across the crack, ie, it is still largely planar?

Or is that wish for a minimalist repair just a "pipe" dream?

I am in Baton Rouge and would appreciate any advice and recommendations for folks who do this kind of work.