Not@home wrote:
We have (had, I guess) a glass shelf in our bathroom, with glass holders
mounted to anchors in the drywall. One came loose, and eventually the
hole in the drywall became to large to set the anchor.

Because of the unique glass holders, I cannot use a larger anchor, nor
will toggles work with the screw I have to use. Relocating the hole
would be problematic. So now I want to patch the drywall and restore
the quarter inch hole.

My plan is to use mesh on the back of the drywall, fill the oversize
hole with plaster, then redrill. I've had good results using this
technique for patching, but I'm a bit concerned that the new hole I
drill will be almost as big as the oversized hole, and the anchor may
not hold. Years ago, I think I heard that wood glue can be mixed with
plaster to form a stronger surface, but my bottle of wood glue says
nothing about this.

So my question is whether mixing wood glue with the plaster will give a
stronger repair and, if so, about what portion of wood glue to plaster
is appropriate.

I'm unhappy, because a few years ago we had two hardware stores near us,
either of which would have provided good advice, but Home Depot has
driven them out of business.

Why don't you take a piece of wood capable of being inserted into the
hole (or a larger hole) with a string attached to the center of the
wood. For instance if the hole is one inch, the wood could be 1/2 inch
stock measuring 1 x 6 inches. Drill a hole in the center of the wood
and knot the string so that it can prevent the wood from falling once
inserted into the wall. Before inserting into the wall, apply some
mastic or thick glue to the side that will contact the sheet rock. When
inserted into the wall, pull on the string so that the glue on the wood
contacts the sheet rock. Let the glue dry, cut the string, fill the
hole in the dry wall with patching plaster, and drill a new hole so the
screw holding the glass holder is secured by the wood rather than the
sheet rock.