Concrete question, underpinning

[wayne64]

I opened a real can of worms with this combo deck / patio project. When I started to remove the old slab (2") that had slates sunk in it, I realized what a past owner had done. They had brick veneer wall installed on the one wall of the house that wasn't brick from the get go. They built it on top of this 2" slab and that explains the cracks I saw in some of it So I have to jack, support and do the footings that it should have had alittle at a time. So the question.
I take it that concrete shrinks some on curing?, is there a strong product that can be pored that, if anything, when cured might expand a tad?
All I can think to do at this point is to pour my deep footings, then make a jack that can be buried in the final pour of concrete under the wall. Angle iron, rod couplings, bolts and a flat plate as a foot for the jack.