Perhaps throw 2 hinges on that old top and use it as an extension for the MFT. Space the hinges so they will fit on the ends or the sides of the MFT. One set of hinge bolts fit in the slots on the side of the table, the other set go into the old MFT Top. Might need some spacers between the old top and hinge to get the heights to match. Add some scrap wood pieces to act as legs on the far end of the old top. The scrap legs can be cut to fit into 20 mm holes for easy removal and storage. [smile]
Regarding the holes in the old top, you can enlarge holes as needed. You can use a marker and put a little dot next to the holes already done.