im having trouble trying to find a edz flashing to fit my ggl f04 velux window. size 660w x 978mm h, no one seems to supply it , i can get hold of edz f06 flashing, which is the same width but is longer, size 660mm w x 1178 h . would it be possible to cut throught the width of the fo6 and then over lap it threfor makeing it shorter to fit my f04 window. thank you for any help