Hello, great work on your trees. Amazing to know that is possible. I am in Melbourne, Aus, where it is marginal (like Cali) for lychee (too far south!). I just read through the entire thread twice. I just bought a Kohala (looks air-layered) and B3 (Kwai Mai Pink). It is spring here which fits with what Tony714 did; although looks like Fruit4you started mid-summer. I haven't grafted before, so I am a bit hesitant to try on my just-purchased plants.
--Did you both use cleft grafts Tony714 and Fruit4you's?
--Do you want young wood for both the scion AND the root stock? It is a bit hard for me to tell if any of these stems/branches are appropriate, as I have just purchased the plant and have not seen the growth myself.
--Since there are already leaves on both, is it too late in the season to graft? The plants were sent down from a warmer climate, so I wonder if they had already started growing for the season. There are small sprouts of new growth at the top of both trees.
--I would appreciate any opinions on the branches in the photos and whether you think some might be appropriate. The first 2 are longan, the second 2 are lychee. A chopstick is included for comparison.