[@HueMan]

So I know I ghosted for like 5 months but if you want an idea, here is my two cents. It's how I used to handle my dnd play by posts I used to DM for.

Make a post every three or four days that moves the plot and anyone who hadn't posted at least once in that time frame gets auto moved. For example, in a fight Person A is calling out commands to B, C, and D. B and C post bit D doesn't by the time you put out the boss post. In the fight summary, it'll read "Person D auto attacks for (whatever value)." If this happens repeatedly with the same people, discuss with them privately. People may be more willing to discuss it in private instead of in the OOC maybe.

In the event it isn't a fight, they go chill in the in or they stay quiet during a travel scene. This way the game keeps moving for those who are in a position to post regularly.

Of course, this system assumes the person didn't tell you anything before hand.