Hi there. Season Passes cannot be game shared between multiple accounts. Since the free pass that came with the Shadowkeep purchase was already applied to your dad's account, you would need to purchase one with your own account to have access. Bungie does not provide support for platform services like game sharing. If you were using it before and now you don't have access to Forsaken and Shadowkeep, then that suggests the sharing was stopped and you'll need to work that out with your dad.