A couple questions for upcoming travel on Aerolinas Argentina

1. Which US airline partner miles can you use to book flights on Aerolinas Argentina? I've tried Delta (Sky Team), and United which seems to also do some code-shares with them ... but no inventory on either of their sites. Do I have to call UA/DL directly?

2. I'm trying to understand AR's policy on same day standby (https://www.aerolineas.com.ar/en-ar/...r-later-flight). This indicates it can be done, but isn't very clear. For instance, is option only available for Diamond members? Are there any change fees?

3. Also it appears that in a standby situation, one would pay the fare difference... which could be prohibitive especially if you're waiting to change the flight 90 minutes before departure, it is unlikely that the discounted fare classes will still be available. The domestic AR flight I want to take is ~5 hours earlier than the flight I am booked on, but is also several hundred dollars more expensive and so am wondering if same day standby could be a better option.

Any first hand experiences with this?

thank you!