I have a damaged quilt somewhere, but have not attempted to mend it yet. It is another dog chew. He pulled it off the clothesline. My plan is to find fabric as close to the color and print as I can and to cut new pieces to fit the chewed areas. This one is hand quilted, so the picking and requilting shouldn't be too bad. Since you made the quilt, do you have fabric scraps left? I would do the same as I am going to do. Cut the triangles or whatever shape, and hand sew them in place. You may have to replace part of the batting too. Picking the machine quilting may be the hardest part.. As far as the border goes, I would remove as much as necessary to make a seam across the border and add the new piece on. If the quilt has been washed the colors may have faded some. You will just have to see how they look side by side. Good luck. Maybe someone else has a better suggestion.