my son subscribes to spotify and I pay for his subscription. i am currently on a free trial offer after which i plan to subscribe but I would like to merge mine and my son's accounts into one family account. How can i do that?
You can upgrade to Premium for Family at https://spotify.com/family and then invite your son by doing the following:
Note: The owner and all members of a Premium for Family plan must reside at the same address.
does the invite cancel the sons bill automaticly?