I have just done all of this, a month ago. Not without problems.....
I suggest that you call
Etihad ASAP and ask them to add your VFF number. Also ask them to remove your
Etihad number. Then confirm online in the "manage my booking" section. Then, AT CHECK-IN, confirm that your VFF number is on the boarding pass BEFORE you walk away. This last step was the key point, which I missed.
I was so wrapped up in the J check-in, "look at me, I'm flying up the front" emotion that I failed to confirm before heading off to the lounge. It cost me VFF Platinum !!
Oh, and the 777-300 ER is perfectly fine. It's a flat bed with all the
Etihad J trimmings.
In fact, I'm also kicking myself that after a late substitution from the 787, I didn't notice that it was one of their rare 777's with 1st class. (Apparently, you can tell from the J seat layout).
We could have upgraded to F for a few thousand
Etihad points. The two pax who walked up to F on our flight looked like AFFers. Smart guys!
The other 6 seats remained empty for the entire flight. Sad face emoji