Didn't know about the Iceland. The SFA should up their game when it comes to updating their website.
The U21s are subordinate to the senior team and can afford to lose a couple of players to the senior team and try out others, especially if they are playing Iceland in a friendly match. Personally, I'd like to see Anderson, Conway and Ramsay involved.
With Hyam, as I said, a player who may very well be playing Premier League football next year cannot be ignored.