We are putting down tile. Have wood floors so had to put down hardback board first. Our house is approx. 28 yrs. Old. Removed the toilet. We have a metal flange screwed into the original subfloor. We cut a hole in the backerboard around it. The flange is under the lip of a PVC collar that is glued to the 4" PVC. When we apply mortar and tile it will cause the flange to be lower than new floor. We cannot raise existing PVC or flange higher than it is. We purchased a PVC Two Finger Toilet Flange that has a pvc sleeve that fits down into the 4" pipe and sit on top of the existing flange. That still will leave 1/2 " lower than the new floor. Can we add another toilet flange extender on top of the other one or is that a bad idea. Is our only recourse to cut off existing 4" PVC coming up through the floor (under crawspace) and put a new longer PVC pipe up through the floor and use the backerboard as the existing floor. We want to tile under the toilet up to the flange but not attach the flange to the tile and have to drill through the tile. Need help soon. We borrowed a tile cutter from church member and need to get it back. Thanks for any suggestions.