I did not fly UA for long time and somehow I forgot a basic issue.
I am sorry this has been discussed before(I guess).

I am UA 1MM flyer so I am keeping UA Premier Executive status.
If I fly on UA but put miles on ANA, can I still have economy plus seat?
My reservation record shows ANA mileage number, so UA will not recognize I am a Premier Executive member.

Shall I put UA number and change to ANA number each time at check in?

Also, if I want to use ANA award miles for UA flight, can I get a benefit of UA Premier Executive? I do not know I could add UA mileage number on the record if I use ANA award miles.

Thanks in advance