An idea implemented on another site (ICCF Webchess) that could be good here?
Each ID/Player has a calendar and is able to select 30 days holiday a year, when player A is on holiday the game goes on hold (which means that player B cannot make a move on his game with player A). All clocks are also stopped for that game.
When player A's holiday allocation runs out then his clock starts again.
It means that player B cannot time out player A when he is on vacation but player A cannot abuse the vacation flag with only 30 days available per year.
Any thoughts, bad idea or good idea?