Family plan only works on Xbox One. If you're on Xbox One, you'll need to add them to your family in order for them to benefit from your Gold Membership. The family plan only works on Xbox One. If they're in your Xbox One family, the benefit doesn't extend back to the 360. On the 360 each individual must have their own Gold Membership.
http://support.xbox.com/en-US/xbox-one/security/add-family-member
Add a new member to your Xbox One family
Creating a “family” on Xbox One helps you manage privacy and online safety settings for children.
Any adult in the family can add new members to the family. Adults and children in the family have different rights when it comes to managing the family. Learn more about who can manage the family.
To add a family member, follow these steps:
Note To add a new member to your family, you must be signed in to Xbox Live.
- Press the Menu button on your controller, go to Settings on your console, and then scroll right to theFAMILY section. Select Add to family.
- Choose who you want to add:
- If the person you want to add to the family already has an Xbox Live profile saved on the console, select that profile.
- The person must then sign in with the email address and password for their Microsoft account.
- Select Add to family again.
- You should now see the person added to the family.
- If the person you’re adding is a child, and you haven’t already associated their account with yours, you’ll need to provide parental consent in order to complete this process.
- If the person you want to add has an Xbox Live profile, but it’s not saved on the console, skip to step 3. If the person doesn’t have an Xbox Live profile, skip to step 4.
- If the person you want to add has an Xbox Live profile but has never saved the profile to this console, selectAdd new and have the person sign in by providing the Microsoft account and password associated with that profile.
- If the person doesn’t have an Xbox Live profile, click Add new and have the person create an Xbox Live profile. Then, go back to step 2a and complete the process.
Note For information about how to create a new account and profile, see Manage your Microsoft account.
When you return to Settings, you’ll see the new profile under Family.