If knowledge and all that is shared how do alts help to boost your mains co?

they dont atm.. there will be an update with Tower that will require all the chars you have.. but until then you dont need it.. just for getting stones scrolls and otjer stuff to help grow your main char

Gear on your alternate characters and the gears respective levels as well as character levels are calculated into family CP which is in return calculated into "Base Family" CP this cp is shared with all of your characters and boosts all of your characters power. So make sure to level up and gear up all of your alts so your main becomes stronger.