A picture would help. Also, my Suebelle did not flower in this awkward spring and has only a few blossoms now. The main propagator for Suebelle in California is LaVerne Nursery and I believe they are all rootings, not grafted. At least, I’ve never discerned a grafting scar on the plants I’ve had (I used to sell them).
White Sapote is native to semi-tropical forests and its natural inclination is to “reach for the sky”. It will do just that – like a telephone pole unless headed back at 3-4 feet. The side branches that come out will naturally grow upwards for 4-8" and then droop towards the ground (as do their forest partner: Avocado trees). The highest area of the arc on these branches will (eventually) be home to new somewhat vertical branches. So when drooping branches have advanced well below the arc (maybe 2 feet or so) then truncate them.
Here’s a view of the Suebelle at my former residence in Rancho Penasquitos.