J availability on UA, BR and OZ via ANA on an RTW ticket for 2?

After a successful ANA RTW booking last year, I’m now trying for one starting mid-Oct 2025. I’m struggling with the final leg from Asia back to the US for 2 in J. I know ANA J is super hard to get, but I’m willing to reposition from TYO to TPE for EVA, or ICN for OZ. Also looking at UA from TYO to EWR.

I plan to structure my itinerary as follows, starting in mid-October and returning the first week of December. Miles are currently making their way to ANA from AMEX.

1. BOS-EWR-IST (UA/TK),
2. IST-TAS (TK),
3. TAS-ICN (OZ)........
4. And then the return to US, where I am struggling. (Currently looking at availability as far out as they go, knowing that I will have to rebook as my dates open up)

Here are my questions:

1. Does UA release any J to ANA for booking? I can see them on UA but not on ANA
2. I also can’t seem to find any EVA availability, even TPE>ORD, which is what I used last year. Has something changed with EVA?
3. When does OZ release to ANA - and how many J?

Any thoughts or recommendations? Many thanks!