Toilets, Sinks, Showers, Tubs and Disposals - Is it possible to repair/replace leaking shower drain in concrete floor condo?

I own a 3rd floor walk up condo with concrete floor/ceilings. My 3/4 bath shower drain leaks into the owners recessed light/shower ceiling below me (causing her shower ceiling to sag and much panic on her part).

After caulking the usual suspects and checking for other obvious signs, I still leak (it ONLY happens when water runs down the drain). I decided the likely culprit is bad drain.

When I realized there might be more mud/concrete than a weekend would afford, I peered into the drain and saw what looks like a hole eaten in the bottom of the pipe - I could be very wrong on this tho...

After 47 years, many houses and small office buildings, I've done my share of DIY plumbing, but this one caught me flat footed.

Not sure where to start...can this even be done? Do I get out the air chisel? Would it be easier access from the neighbor's shower ceiling? Should I cap the drain/supply and turn the space into linen closet? Thoughts? I don't need this shower now, but am thinking about resale.

Any and all help appreciated.

Thanks in advance,

Jan

I would open the neighbor's ceiling, replace what's bad & patch it.

Kind of sounds like the downstairs ceiling is wrecked and needs to be replaced anyway, so that might be a good place to begin. If it provides the access that's needed, it just may save you from tearing up your floor.

Gotta be able to get at it from below.... And her ceiling should be replaced anyhow.