Elec,

You can try topwork it. Not too hard. Use barkgraft. Apples are fairly easy graft to take. Look at the link below.

Here is a link that might be useful: Topwork crabapple

This post was edited by tonytran on Sat, Apr 20, 13 at 8:30

do it yourself. Use chip budding method. You can
do this in spring. Be sure to use a leaf bud to transfer
to a stock. Cut the chip in the stock, then the whole.
Have the budstick ready. Cut the "chip" first, real shallow
then do the "top" being sure to cut under the chip to leave
like 1/8" of green to slip into the slot. (look up pnotos of how to do) Be Very ready to put the bud in, time is of
the essence. While you may not touch bud surfaces you may pinch the very top with your fingernails. slide
in within 10 seconds. Can't? put on your tongue upside
down so you can pinch the top to place it. Use strips
of a pretty sturdy plastic bag 1/2" wide to wrap. Do this
carefully and make sure it is waterproof.
Best results are dormant to dormant Or dormant twig
bud to a stock that has just started growing. All buds
are not out at the same time. If the stock is growing
the bud should "take" in three weeks. Unwrap and
check. If it is firmly attached re wrap top, then bottom
leaving the bud exposed. Cut off the top to force your
new bud making sure you seal the cut by any method.
wax from a candle, pruning sealer, 3 layers light
latex paint.

Hm, I'll look into it. The crab apple is an older tree as well, I'm going to guess at 50-60 years old based on its location.

Below is my apple tree I'm looking to "save".

For chip budding, I need to find new growth? The crab apple is always putting shoots up where I DONT want them, I will have to look for some to use where I DO want them.