Thanks for the advice! I wanted to try it on a watermelon that is not doing particularly well. It is growing, but very very slow and thought the extra root system might help. I changed the soil out mid summer, and the root system is very weak.
I've tried approach graft with mango rootstock, but never tried it on jaboticaba. Yes, mango is much easier to work with, and though I've been successful with cleft grafts on plinias, the approach graft on very small scions might be tricky. I'll let you know how it goes, thank you!