I plan to put in some apples next spring and am working on figuring out how many I can fit and what varieties to plant. Right now I'm thinking mostly edible crabs on M111/G41 or M111/G65 and maybe a few M111/G890 interstems.

But one area in particular I'm considering is a bit iffy in terms of how good the soil and drainage is and the space available for the roots to grow out. I really don't know how well trees will do there and was also thinking of multi-grafted trees in this area. So I was thinking of putting in M111/G890 in that area and just letting the interstem part grow out as trees and top work them with a few different varieties per tree later once the base G890 has grown out for a few years. I always hear about people top working trees when they decide they don't like the variety, it does poorly, etc., so this would basically be like doing that but growing the G890 "tree" knowing I wouldn't like it as the final plant.

Since the Geneva rootstocks as a whole seem to have good resistance to some common ailments it seems like the base tree for my top worked grafts should be a good foundation tree. And when I top work the G890 tree later, the grafted varieties should grow strongly and hopefully fruit relatively quickly because of the strong base plant.

Is there a reason this is a bad idea? Does anybody else use this approach for multi-grafted trees?