I would do it, but try not to over-rely on this plot device. For instance I think it would have been good in GF III if one of the capos operating under Don Lucchesi in Italy turned out to be a grandson of Don Ciccio (maybe the No. 2 guy ready to take over in the event of Lucchesi's death, pointing of course toward GF IV).

But you can go to this well too often. Once or twice a movie maybe, that's enough.