SMC (sheet molded composite) has a mold release agent built into the material to help parts be removed from the mold easily under mass production conditions. Normal fiberglass resin won't adhere to SMC and will eventually fail because of this release agent. Proper SMC resin must be used if the work you are planning to do is going to last.
Or at least that is what I remember reading some time ago.
Other products that may be of help;http://www.pliogripbyvalvol...SMC_Panel_Repair.pdfhttp://3mcollision.com/prod...-adhesive-08219.html