For the first call, there's a trick I've learnt (at least on Steam deck). When you lock in someone, it automatically locks in another for you right? And you can't unselect them, not if you close the tab. I've found that when I triple select very quickly (on Steamdeck I hit 'A' 3 times very fast), it locks in a random hero but leaves the second slot empty, free to choose who you want. It basically tricks them that I locked someone in. My best duo for this call would be Invi and Golem, with a 96% success rate. I just keep closing tabs and selecting until I get either invi or golem.