Enable family sharing when no apple device is available

You need an Apple device to setup and manage Family Sharing. It cannot be done on a PC or non Apple device.

You can just sign with your Apple ID (that holds the subscription) in the TV App on the Firestick.

Apple TV can be used with AirPlay to play content from a device or computer, or if you set up Home Sharing it can access any active libraries of computers on the same local network set up with the same Apple ID. The Apple TV can also access the purchase history of the user that sets it up. Family Sharing comes into play when you have an existing family group that have made purchases as these may be accessed via {Media Type} > Purchased > Family Sharing > {Member}. Apple TV cannot be used to create or accept invitations for family sharing.

See Set up Family Sharing - Apple Support.

tt2

See the Sign in on Apple TV section in Sign in with your Apple ID - Apple Support. I believe you can sign in with multiple accounts that are not necessarily connected through family sharing and switch between them on demand.

tt2

Just make sure purchases are set up so they need a password, and there should be no issue.

The Apple TV app on 3rd party devices is limited to access to the iTunes store and AppleTV+ subscription services.

There's nothing more the Firestick can access.

You can also set up Parental Controls on the Firestick.

https://www.amazon.com/gp/help/customer/display.html?nodeId=GB8P5MQSYFYHPCQ5

Yes, Signing in with your Apple ID on the FireStick would make your Apple TV+ subscription available to be used on the FireStick.

Do note, that the AppleTV+ subscription only covers Apple's Original content. Movies and shows from other producers or studios would not be free. They would still need to be purchased or rented normally and paid for, which is why I suggested password protecting purchases. So they don't run up a bill on items not covered by the subscription.

List of Apple TV+ Original content - Wikipedia.org

Clearly sharing your primary Apple ID isn't going to work. Family sharing can only be set up with appropriate devices (don't ask me why). A remaining option might be to create a separate ID for your children to use, and subscribe to Apple TV+ with that account.

tt2

You only mentioned the FireStick. Not other devices your family owns. No other devices need your Apple ID if all you want to is to provide access to the Fire Stick. You aren't really sharing your ID. Your simply signing in yourself with your Apple ID on the FireStick.

They don't need to have your password, and they don't have access to anything else.

Outside of other channels, the iTunes Store content, such as movies and Tv shows not part of the TV+ lineup will incur other costs.

Content in the TV+ subscription: https://en.wikipedia.org/wiki/List_of_Apple_TV%2B_original_programming

Yes, you would need to update the password on the Firestick each time you update.

Not sure what you think is going to happen with your Apple ID really. Its just there to access the subscription. They can't do anything else with it.

Your other option is to buy a cheap used Apple device like an iPod Touch and manage Family sharing from there.

But that comes with its own set of issues.

Anyone using the device has access to the content of the signed in account. You cannot setup Family Sharing unless you're using a Mac or an iOS device.

tt2

As Phil says password protect purchasing then you can use a single account if that is easier. That's certainly how I managed things to start with for my family.

tt2