Thank you for your inquiry regarding this item from Prime-Line Products. If the doors have large pre-drilled holes to receive regular door knobs, the mounting screws of the rosettes will not have any wood to screw into as required for installation. The square metal spindles of these glass knobs require only a 3/4 inch hole for installation, so perhaps the best option would be to apply a hardening-filler that can fill the large knob hole, to then re-drill with a 3/4 in. bit. This would provide for a solid surface in which the Passage Door Latch Set rosettes can then be fastened to. If attempting this method of door prep, use protective measures to avoid getting the filler on the finished surface of the door.
For additional questions regarding this item, or any other product manufactured by Prime-Line Products, please call their toll free number at (877) 649-9740, or contact them by email at email@example.com