what is the right way to fix stress cracks in fiberglass

[34mike]

I have an older fiberglass body made around 1993 and I am starting to get stress cracks in some places coming thru the paint . I am planning a repaint soon and would like to know before I take it to the body shop how this need to be fixed. The stress cracks are spiderweb shaped mostly around the A pillar and where the top transitions to the trunk on the side of the car. Should the cracked area just be ground out and filled with fiberglass or is there work to be done behind the crack first (reinforcing with fiber'gls mat) or am I in serious trouble with a body that has outlived its self proably cant see it in the picture but there little lines under the paint going from lower left in pic to upper right.