I have tried few years ago to graft hazel and i have done it on dormant root stocks with cleft grafting method and from about 15 grafts i had only two success.
This year i tried to graft again hazel and i done it too late when sap already started to flow and i had from about 20 grafts 0 takes.
Hazel is difficult to graft because of thin bark and cuts on scion and root stock must be perfect matched.
Easiest way to propagate them is by rooting suckers by adding moist soil on them, i have added one video about that in this topic.