For some small scions, I have done 2 scions in a cleft graft. Line one up on side and the other on the other side of the rootstock. You can remove one later if both take.
Dolgo rootstock are seedlings if you wish to do some more experimentation.
I have grafted some on seedlings with mixed success. I have had better luck with growing rootsuckers from wild trees for a few years and then topworking on them.
I have also used rootsuckers from trees I purchased.
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