Google 'air-layering' for specifics on the method you are contemplating. Grafting is much more reliable than air-layering for all apple cultivars, as far as I know. Different cultivars have very different take-rates for rooting cuttings (and layering branches). Sounds like your cousin may not have done something right.

I wonder why your brother-in-law wants to cut the tree down.

You might want to consider contacting a local orchardist to see if you could get some help with grafting. I bet you could find someone that would be VERY HAPPY to help you save a threatened apple cultivar. Many would probably accept a scion for their own use as payment for their service. If you can't find someone locally, post a request on the Fruit and Orchards Forum.

You might make a call/visit to your local extension office. You never know.....you might very well get some help there.

i would direct you to the fruit forum ...

and ask there.. if there are any providers.. who will do this for you ...

why not pay to have it done.. and be insured of success ...

or try googling something like 'custom grafting of apple trees' ....

its grafting time right now.. you might be able to have trees back this summer.. or fall at the latest ... i dont know how it all times out with apples ...

ken

curiosity got the better of me.. check out the first two links ...

ken

Here is a link that might be useful: link

If you have an apple rootstock, grafting the apple you want to save onto any apple should work well. Now is the perfect time of year. I've grafted onto mature trees and also small crabapple seedlings two or three years old. For me the way to success was in wrapping the graft well to prevent dehydration. Remember to align cambium on the scion to cambium on the rootstock.