Depending on the pattern and previous quilting design, you could use a decorative stitch over the seams. Make sure to catch the fabric on both sides of the seam. That will anchor the fabric to the batting and backing and help reduce stress on the seam. If there is a pattern to the separation, sew over all the affected seams and it may appear to just be an intended quilting pattern. I have tried fusing seams before and have not been happy with the result.