This is now available in baseball but not football. I only see the team in that league, not all in football. I have to go to each league to see whether that player is owned.
Also, there is a glitch in football. I have options set to desktop view but when I click a player, it goes to mobile view for some reason.
Could you make a post in TechSupport about this, not sure the desktop view is supported on the football site right now.
You have a separate person for tech support?
No, just need a separate post for each issue so I can track each one separately. You don’t have to post it, but then I probably won’t remember to fix it 
Baseball has this already.
Will start working on this today.
There is now a box that shows a player’s current transaction in your other leagues.