I have a ticket purchased on NZ from LAX-AKL next Feb. I'm wondering if I now purchase a ticket on UA or US from PHX-LAX if I'll be able to check in all the way through for my NZ flight while I'm in PHX or if I'll have to wait until I get to LAX.

Previously this worked because I had a UA flight from PHX-LAX and my LAX-AKL flight was a UA codeshare flight on NZ. But my flight will be purchased separately this time so I'm wondering if the same benefits will apply.

Thanks for the help.