trying to save a heritage apple tree

My neighbors up the road stopped by this morning and asked if I'd cut down an old apple tree. It had a bad ant problem and had stopped flowering about a year ago. I'm not set up to graft, nor to start cuttings. Although I may get some rooting hormone tomorrow if I can find it in town and try to take a couple cuttings from the branches. I told them I would, hoping that if I did I could find some way to try to salvage it. When I got there I found several small trees sprouting from the roots. I dug those and tried to get as much root as I could, but even the roots were pretty much dead. The tree still had plenty of leaves but almost the entire trunk of the tree was bored through by large black ants. I checked the growth rings (didn't count them, I will do that tomorrow) and the tree had only been growing on about 1/4 of the trunk for several years.

The story is that the tree was planted some time in the 1930s or 1940s, and it was some kind of cider apple tree brought here to SD by the people who took over the homestead on that land after several failed farmers. I'm not sure how true that all is but I can verify the age of the tree tomorrow because I kept all the wood for smoking, but either way I'd like to see that old tree live on somehow.

So what I did was I potted all the sprouts I had deep in 12 inch pots. The soil is moist, but not soaked. I removed most of the leaves from them. Some have apparently decent roots, some don't. I have about 10 of these in pots. I put them outside under the north edge of my deck, where it's shady and cool (relatively), but there's a fair amount of indirect light.

Is there anything else I can do to help them along? How wrong did I handle them? Is there any realistic chance that they'll survive? I wish I'd had more time to plan this, but they pretty much were going to take it down today, and were just offering because they know I'm always looking for good smoke wood.

Thanks.

Mulch the pots heavily with wood chips and any local mushrooms you can find. Ants have a taste for fungi, and they may have grazed away a lot of the beneficial mycorrhizae on the roots. You need to rebuild the mycorrhizae over the winter so that the roots are strengthened before you plant out the new sprouts next spring. Another good source of beneficial mycorrhizae is leaf litter under oak trees. If you have an old, well-established oak tree in the neighborhood, dig some soil and leaf litter from under it and use it to mulch your new apples. If the oak tree is in your back yard, you might even want to half bury the pots with the apples under the oak tree for them to overwinter.