Actually, I'd think Sea Foam might hold that record, Michael. The way the parentage is listed here is only partial. If you check the references you'll find...
Modern Roses 10EDIT Book (Apr 1993) Page(s) 540.
Sea Foam® Shrub, white to cream, 1964, (('White Dawn' x 'Pinocchio') x ('White Dawn' x 'Pinocchio')) x ('White Dawn' x 'Pinocchio'); Schwartz, E.W. Description.