@Apos Sure, that could work. In fact I've been doing something roughly similar by having ties to important NPCs in the plot given to specific characters I knew would enjoy certain roles. For instance in the long arc I was running on Eldritch a major villain was a PC's Sire.
Notice however this would probably be a very bad idea if I was staff, since it could be taken as showing favoritism to certain players. As a plot ran by a lowly player though? No shits given.
Either way I would be careful when designing the plot though to make sure those roster-characters weren't too important to the detriment of every other participant. 'Regular' PCs should have the ability to make just as large an impact to the story's arc else why would they bother playing if they're essentially sidekicks to the real protagonists? If you know what I mean.