I just did that on my Trillium
. I used hardwood splints and fibreglass resin. I cleaned up the hole a bit, then got some hardwood and split it into pieces that would fit into the holes. I dipped the sticks in some resin and tapped them into the holes. 24 hours later everything was solid. I trimmed and sanded and then drilled new holes for the door. It fits like it's 10 years old instead of 40.