Hi,
I haven't tried this but it works for other things! I would try soluble Vilene bought by the metre, have that on the bottom then the fleece and work from the top of the whole sandwich. I keep thinking I shall try this after seeing a beautiful lap quilt, fleece backed, made by a Bernina demonstrator for her mother. It had been well used but still looked fine. She had chosen a wonderful purple colour for the fleece and in memory had cotton quilting fabric on top.