Can you explain your building details a bit more?
Do you have any pictures you can share with me?
so they are moving/migrating in a horizontal direction
Sorry for the delay.
The foam jacking and piles serve different purposes.
The foam jacking will fill any voids under your slab and then possible lift/level your slabs to a certain level.
Then I would assume the piles would be used to retain the slab from moving in the horizontal direction.
I would think the foam jacking would be a reasonable procedure to make sure all possible causes/issues are addressed.
I hope this helps.
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They could be designed to resist both of the slabs if one slab is pushing on the other. The only issue I might see is to make sure that the inboard slab pushing on the outboard slab would not crack either slab at the interface between the two.