Michael,
Lucien Tyng was looking at acquiring land to the NE of the present site, where a residential development now exists. In fact, Flynn designed 3 nines in case he acquired the land. In the end, it was deemed not as suitable for golf. One of the mandates to Flynn was that 18 holes were to be in play at all times. This meant that some of the old course was used while Flynn's complete redesign was being implemented.
The last holes to be built included today's holes 1,2,3,7,8 and 9. Holes 4,5,10-18 occupy ground not previously used for golf. Only holes 1,2,3,7 and 9 occupy hole corridors as used by Macdonald. Of these, all of today's greens, bunkers and tees (except for 7 tee) are Flynn and only the beginning of 1, end of 2, holes 3,7 and 9 occupy the same the same ground as the Macdonald holes. Of these, 7 green was raised in position and 9 green was lowered.