How do I assign multiple user_id's to one work order record

i got a question ive been scratching my head for a few days on a solution to a problem. I currently have work order that we assign a single user to and im trying to figure out the best way to assign multiple users to a single work order so if multiple people work on one work order at the same time they will have their own time card as well. I currently have a belongs_to association on the order model and on the user model I have has_many :orders. On my form i have a collection select that accepts multiple: true and in the database (pg) under the order table i have a user_id: integer column. Is there any additional steps to make this work? also in the order controller, i have user_id: [] under the order_params to accept the nested array or selected users in the form. Any pointers would be greatly appreciated.