Can holes over a foot in diameter in an inground vinyl liner be patched or does the liner have to be replaced?

Your best luck with a hole that large is going to be if its against a hard surface in the pool, IE: floor area , wall area below water.

You have nothing to loose , your going to most likely need a great underwater glue and very large patch material, avail from a pool professional.

A good underwater glue and site is Union Labs, Inc. www.boxeradhesives.com

No more underwater Ice Hockey with a liner pool either.

They also have an email avail and can direct you to a dealer in your area or online site for purchase. good swimmng getapool.com

You may also want to visit mrstickys.com and check on their Underwater Glue. Visit the FAQ's that describe how to repair a pool liner underwater.