How about creating a square template to fit just inside the seam line of the damaged blocks, draw around the template with a chalk marker, cut the squares out carefully by hand, then reinforce each square with permanent iron on stabilizer to support the loose weave. Now cut 4 strips of matching fabric to create a new border for each square and attach strips by machine, like a binding, mitered or squared. Re position the repaired blocks on the quilt using a spray adhesive, machine baste in place, and finally machine stitch each block in place, like an applique, using a fancy stitch maybe a blanket stitch! I am sure there is a scripture somewhere in the Bible that addresses this situation for you and I am also sure your MIL loves the quilt and the love you put into it which is the most important thing of all.