I would make sure one of you stands by the door to prevent it closing, the train can't leave until everything is closed up.
Be carefull when actually doing this, if the guy already blew his whistle, and someone of your party is still blocking the door, you can get fined!
I did this last year, because the guy actually saw us still running up to the correct carriage, and he blew his whistle, so we started to run like crazy, my friend lost her phone (fell out of her pocket while running, and I stood inbetween the door, yelling at her to come (or not, her choice at that moment), and I obviously got lectured by the guy.
I knew I was in the wrong, but it was a spur in the moment thing / panacking kind of thing. He let me off the hook, because I already told him 20 minutes earlier my friend was going to get there very close to leaving time (as her train to Brussels was late, so it wasn't her fault).