My partner is flying YOW-YYZ-LAX soon, and I'll be joining her YYZ-LAX (AC 793 from YYZ-LAX which seems to typically depart F69). She has a 5 hour YYZ layover. The regular trans-border lounge remains closed. Are we able to use the trans-border express? International? Is it even possible for me to get airside with my ticket to meet her in the domestic lounge, realizing we'll have to exit to go through the US security checkpoint and US Customs? I'd prefer the latter, only because I am way more acquainted with the domestic portion of the terminal than trans-border.

Thank you in advance!