Game Sharing DLC

The DLC is account based, so only the account that bought it has the licence. Although DLC should be game shared in most if not all cases, so if your sharing it should be. Are you referring to game sharing?

Are you playing on the account that purchased the DLC, or are you playing on a new account that is game sharing with the account that purchased the DlC? If you are Game sharing with your dads account or the account that bought the DlC. Then you wont be able
to use any of the DLC. Game sharing/ Homing only allows you to play another persons games. It will not allow you to play the DLC. If you are playing on the same account that previously purchased the DLC. You should be able to go to Fallout 4 in the store and
re download the DLC with out paying for it.

So, the DLC sharing is not really full, but only semi-sharing, therefore I also have to purchase DLCs despite XBOX HOME share, right?

Meaning that buying full games is useless because you can't have full game share 😕

If the base game is all working through game sharing, then unfortunately the publisher has made the DLC specific only to the purchaser of the DLC.

Some Publishers are not allowing some DLC to be shared, and they need to be purchased individually.

Sorry for the bad news.

ESO does not allow game sharing of ANY DLC. I've experienced this when my wife and I both played. The main game will game share, but you'll have to buy the DLC twice.