Thank you very much, Jon!
I've followed her blog, full of beautiful tatting, free patterns and a lot of useful hints and clear photos. In may she posted about the vintage wheel and how she cleverly used a technique to tat the center ring. That is, the technique is a single shuttle loop-tatted ring, I haven't used it in my wheels, as you read in previous post.
But then I had to find a way to tat the half-wheels.
Aunt Priscilla said to tat a ring 1-2-2-2-2-2-2-3+2 (7 free picots) join to a middle picot of the insertion. Then leave bare thread (she didn't care too much of cutting and tie) and start the ring of 6+6 of the wheel, joining one of 7 picots of the center. You must close the half wheel with 7 little rings 6+6 and 7 larger rings of 4+2-2-2-2-2-4.
First problem: there are 4 picots in rings of the insertion to join to. Which is the middle one?
Second problem: first ring in the round is a 6+6, last it is a larger one, I can't see a way to tat continuously all wheels.
Third problem: if I used the same method used in the wheel to climb from center to little ring, I'd had to hide (where?) one end more.
Fourth: both in text and in the picture also little and large rings are joined to the previous row in a "middle" picot.
--> A solution for the third problem, a guess and a compromise.
Solution for the center ring came from Jon's blog:
A guess: what if I join 2 picots for each ring in the insertion? It seems it's working.
Compromise: I have to accept tatting each half-wheel separately, with one end to hide. One is better than two, this time.