If you do find yourself having to cut through a nice ceiling, it's not as bad as it sounds if your ceiling is nice and smooth and flat, and preferably painted matt white!
This is one of mine where I had to cut a section out to do a C/H pipe repair - or have to rip out half the bathroom above it.
Just noticed a couple of small brown stains on the kitchen ceiling today, from our main bathroom above. I was expecting a leak somewhere, but not the one I actually found - which is a very crusty looking central heating pipe under the bathroom floor. I can't actually get to this from above as...
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When you saw through from beneath using a plasterboard saw or similar, it will break away plaster on the other side, and also tear away the thick paper backing you get on plasterboard - and you can see this in the slightly messy edges to the trap I had to cut out.
But if you then cut all this damage back with a knife, and put some bits of wood across the hole, and secure it with screws, you will find you can then screw the removed section to it and end up with it absolutely flush as checked with a straight edge in the attached. Just make sure you pilot the screw holes and remove any damage on the back of the plasterboard where the screws have come through too.
Fill the screw heads and the saw slots (I use white two-pack filler to do this as it sets in around 15 mins and doesn't shrink so its easy to get it dead smooth). Touch in with paint and job done. You'd never know I'd taken such a large piece out.
Another handy gadget I have for jobs like this is a USB boroscope - which you can buy for between £10-20 on ebay. It is a tiny camera on the end of a USB cable with a circle of tiny LEDs around it - with the whole thing being around 5mm diameter. They usually come with a 90 degree adapter too. Plug it into a laptop (or some smart phones), drill a pilot hole, and you can have a good look behind the plasterboard before starting to cut blind.