[quote=@Ashevelendar]
[@Ammokkx] That should be done via a GM post, I think 
[/quote]

It's not the GM's job to babysit the players completely and keep them informed. Players should inform themselves when a character moves through space and time, the GM should not have to make a separate post saying 'this character shows up here now'. 

What the GM can do is react to the character moving, but if there is no need then there is no need. In my own roleplay, players are free to move about established locations. I've had multiple instances of people outright ignoring characters, sometimes even [i]my[/i] characters, because they didn't read. That's bad.

A player should keep themselves informed on their partners' behavior in case there are details they should know, and not be retrospectively fixed.