Moving from Xbox 360 to Xbox One and Family Sharing

As the family sharing option on the Xbox one is a little bit different to the option on the 360 it is definitely recommended the way you describe it. Set up the adult account and get it a gold subscription. Then set up the child account(s) and add them
to the family and all the family associated accounts are able to use the gold subscription as well as all the digital purchases of the parent/adult account. And of course you can also add another parent/adult account, too.

Only getting a gold subscription for the child account only works for the specific child account and will not be valid for the adult or other family associated accounts.

Sorry but the Family Gold plan has been retired and there is no way to transfer a membership to another account.

However, if you had plans to purchase an Xbox One console you can share the membership with your family on the Xbox One console without restrictions. The Xbox One sharing plan does not transfer to the 360.

He dosent have a xbox live account its family share so there's only one subscription

Now I'm a bit confused.

What exactly do you mean by "kid profile thing on your account" then?

Do you have an adult Microsoft Account, and is the kid added to
https://account.microsoft.com/family with their own child/kid account, or what do you mean exactly with the "kid profile thing"?

Ideally, each family member has their own Microsoft Account and Gamertag, so each person can save their own gaming progress and doesn't unlock achievements for someone else.

The family sharing is done on the Xbox One console. One person that owns a Gold membership can share that membership to one "Home Console", and everyone playing on that console can benefit from the Gold membership and the games that person purchased.

The Xbox 360 does not have the concept of the Home Console sharing. So if your kid is supposed to play online Multiplayer on the Xbox 360 (a real Xbox 360 console, not an emulated Xbox 360 game via Xbox One backwards compatibility), each account playing
on a Xbox 360 would need a separate Gold membership.

Yes, the xbox live gold shares between the Xbox 360 and the Xbox One on one account, so if you have gold one one you have it on the other for free, just log in on the same account on both devices, but only one can be online once at a time.

The My Home Xbox feature to share gold does not share across to xbox 360 backwards compatible or the real xbox 360, so if they need to use the xbox 360, they will each need gold to play on that console.

About the xbox 360 gamer profile reset, can you explain more about that? If you mean moving to Xbox one from the xbox 360, your achievements are not reset - but you may have to rebuild your progress on the Xbox one version of the game if it's not backwards
compatible from xbox 360.

Sorry but there is no Family feature for the 360. There used to be one but it has long since been discontinued.

As you mentioned there is a family sharing feature for Gold memberships on the Xbox One though. If you were to get one of those consoles and set the console as your gamertags Home console then you would be able to share out the membership to your family
members on that console.

I also wanted to mention that they are bringing backwards compatibility to the Xbox One console this winter so you'll be able to play some of your Xbox 360 games on the Xbox One console.