I'm making my own home-brew sirens for my campaign and im still pretty new to home-brew. I wanted to have a sirens song both incapacitate and charm, i need movement still available because I wanted the sirens song to force the player to move towards the siren. It'll only last a turn and sirens song will be a special ability and will have to make a recharge roll after use, so its not going to immediately kill the player if they get charmed by the song. Is this fair?

How about charmed and forced movement? 

Anything can be “fair” as long as you balance the features give it an appropriate CR. Yes, a monster can (and many do) apply multiple conditions simultaneously. Probably the most common conditions that some monsters combine are grappled and restrained. Also, some conditions  also automatically include other conditions too, such as the unconscious condition which also includes both incapacitated and prone.

What Save Throw type and Save DC did you put on that ability? What CR for the monster?