What you need to do is ask around for scions. Wes Rice may be able to get what you need or could point you in the right direction. I’ll try to help you get them, as well.
Yes, the easiest way is to hold off on wrapping the scions, do your cuts first and then wrap them prior to setting them.
If the trunk on the rootstock that popped up is enough diamter 1"-1.5" then you can certainly do a bark graft on it as well. It’ll depend partially on the caliper of scionwood you receive as to whether you’ll do a bark graft or a 3-flap graft.
Let’s try to get wood for you so there won’t be any need to order two trees. That’s worst case scenario.
Keep in touch. Let me know if you’re having difficulty and I’ll try thru my friends to get those cultivars for you. I would write Wes a letter to begin. Tell him you’ve been talking to me on a forum and now you need his help acquiring Warren 346 and a partner for it.
Dax