Best way to plug holes in plasterboard?

[Rollerball]

One of the water pipes in my attic sprung a few pinhole leaks the other day leaving a few pieces of plasterboard 100% saturated. The pipe has now been replaced and the plasterboard is drying out nicely but three holes were the result of the leaks - two of the holes are about 1.5inches across, the other I can put my hand through.

Once the plasterboard has fully dried out, what's the best way to patch the holes? I don't really want to replace the plasterboard for various reasons. The affected ceiling is in the utility room that houses my boiler so any patching doesn't need to look perfect.

 

[foxhole]

Plasterboard is severely weakened by being wet, best replace one large section rather than trying to patch.

 

[Rollerball]

That's a pain. Okay, thanks - looks like I may have to find someone to replace the boards. I have very good airflow in my attic so the single piece of noticeably affected wood (one of the very short pieces that bridge two joists) has already dried out and some joists which were damp underneath (in contact with the plasterboard) are also drying well. There's no signs of mould and the wood is solid.