here's the situation. i currently have an old formica countertop. i am planning cover it with marble tile (12" x 12"). i want to sandwich the undermount sink between existing formica and new marble tile. do i need to grind the bottom of the tiles that will surround the new sink since the flange of the sink will be higher than the existing formica, OR, should i cut out the formica to make the sink flange flush with the other formica surface?