When are new players added to squad update?

What signals a new player to be added to a squad update? Say a youth player is called to be on the bench, but not subbed in, will he still show up on an update? Or does he need to play in the game? 

how long until the update occurs?

sheffield Wednesday had 2 youth players, Bailey Cadamateri and Joey Phuthi on the bench against Huddersfield (Oct 7) but they did not play. Can I expect them to be added soon? Or do they need to have played?