Making a bedspread into a heavier quilt?

I have a bedspread that I have already had the company replace once because it tore very easily at the seams of the quilted block pattern on it. I would like to prevent my new one from tearing by turning the fluffy bedspread into a heavier, more dense quilt. I thought maybe I could stitch along the seams of the pattern, but that would not "flatten", if you will, the whole piece. Are there any quilters out there who have suggestions for how to go about this?