TLDR; nope, splitting PNRs doesn’t keep priority.

The lack of replies must mean there may have been bewilderment. Battlefield results indicate that perhaps being an AA Exec companion card holder and reasonable LPs (not enough for Gold though) last year just coincidentally placed my wife in #3. Within 30 minutes of boarding, the battlefield played out as I originally thought. Pic attached, but she fell from our PNR hard and fast in the final minutes.

Fingers crossed as we just boarded. With a little kid, I took the bags on the earlier and she’ll have to run if she doesn’t make this or the next flight.