Link Xbox One to Xbox One

There's no system link on the Xbox One. Only the old Xbox 360 consoles had that feature

Also what your doing is considered marketplace theft and could get you and your friend permanently banned if caught. The 'home' xbox feature is meant for sharing games and gold accross xbox one systems that YOU own. NOT with friends.

So id stop trying to share your games with your friend all together as youd also lose all you accounts content without refund if it gets permanently banned (i.e. dlc,games,remaining gold membership, remaining marketplace currency)

What are some specific examples of marketplace theft?

Marketplace theft includes, but isn’t limited to:

Getting, asking for, or using redemption codes illegitimately

Transferring licenses to your console from an account that you didn’t create

Using a system glitch or loophole for financial gain

Using any sort of “shared” account to avoid having to pay for games or content

Successfully redeeming or giving away a code and contacting customer support claiming the code didn’t work

Attempting to defraud Microsoft or authorized agents

Fraudulently transferring content licenses

Sharing account credentials

Asking to be added to someone’s third party subscription (such as Netflix, Hulu, etc.), in order to avoid restrictions or payment

CONSEQUENCES

A violation of the Microsoft Code of Conduct may be cause for these or other actions:

• Automatic assignment of a new Gamertag, if you create an inappropriate Gamertag.
  
• Content deletion, if you create or use inappropriate Content.
• Restrictions (e.g., communications, multiplayer, account access) on your use of Xbox Live services, if you abuse those services.
  
• Permanent suspension or device ban, if you commit an egregious violation that includes, but is not limited to: hacking, modding, profile tampering, fraud, trading or stealing accounts or Gamertags, severe racial remarks, impersonating Xbox staff, displaying
  nudity, repeatedly creating inappropriate Gamertags or profile content, distributing URLs to phishing sites.
  
• Permanent suspension or device ban, if you try to avoid suspension with alternate accounts and/or devices.
  
• Permanent suspension or device ban, if you repeatedly commit violations.

UPON RECEIVING A PERMANENT SUSPENSION, YOU FORFEIT ALL CONTENT LICENSES, GOLD MEMBERSHIP TIME, AND MICROSOFT ACCOUNT BALANCES ASSOCIATED WITH THE SUSPENDED ACCOUNT.

Hey there,

I think what you're referring to is sharing your games with your friend through the home xbox feature. You see, there's never an option to link two accounts. That's never possible on the first place so its impossible to transfer a purchase from one account
to another.

You might have thought that you used your own account to purchase the game but if the purchase is showing under hers, then its her account that was used and not yours. Having a Gamerscore or an achievement from a game is not a valid proof. It will all come
down to your billing history or billing statement from your bank.

@BluePixie14

What it sounds like is that your friend changed their Home Xbox back to their own console. So you should have your friend designate your console as the Home Xbox.

@KingGryphon

Only in very specific scenarios is this considered Marketplace Theft. Generally-speaking, it falls within the parameters of the Xbox Live Usage Rules page that I linked to you before from the Microsoft Services Agreement page:

http://windows.microsoft.com/en-us/windows-10/music-movies-tv-usage-rules

Usage rules for digital games purchased on Xbox Consoles

Xbox One Digital Games

How many consoles can I use a game on?

You'll get a device license and a user license to every game you download from the Xbox Store.
You can designate one console as your “Home” console and multiple users can select the same console for their Home console. The device license will automatically attach to your Home console, even if it’s not the console you're making the purchase
from. As the purchaser of the game, the user license will be associated with your Xbox Live account.

Who can use my game?

Anyone can use your game on your Home console under your device license. When you log onto any other console with your Xbox Live account, you may use all games to which you have a user license.

Can I change my Home console to a different console?

You can change which console is your Home console up to 3 times during a one year period (365 days). When you change Home consoles, all device licenses for digital content will move to your new Home console and will no longer be available on your old “Home”
console.

Xbox 360 Digital Games

How many consoles can I use a game on and who can use it?

You can use games on the first Xbox 360 console you downloaded it to. Access to the game will also be granted to all users on the first console. If you transfer the game using a memory unit or other storage device, you'll also be able to use
it on other Xbox 360 consoles, but you’ll need to sign in to Xbox Live with your Xbox Live account on that console before accessing the game.

I had a gaming lounge in my area once - it went out of business...