How can I share my Apple Music subscription with friends?

To keep things simple and short, you're not going to be able to do what you say.

An Apple ID can only belong to one Family Sharing group at a time.

You can only have one main Apple ID on a phone at any one time. You can use a different ID for some secondary purposes but I don't think any of those will achieve what you want to do.

Basically you are are only supposed to share among a close group of people (for example, those who you would trust with your credit card), not just any group of friends.

Only works when the other people are in your Family group and people cannot be connected to multiple family plans. There is no other solution, sorry.

You are correct that having them log in with your Apple ID is a bad idea, not only for security reasons, but you will find that each Apple ID can only play from one source. If another user attempted to use a different device using the same Apple ID, you would find the music on the first device would stop playing and you would not be able to both listen at the same time.

You must be in a Family to share an Apple Music subscription.

Creating a fake child account to bypass Apple's Family Sharing rules could violate Apple's terms and conditions. If Apple detects this, it could lead to penalties such as account suspension or loss of access to the Apple Music subscription. If your account is suspended you would lose access to that "Apple Music replay thing that you really like"....

This workaround could also lead to problems such as app sync issues or restrictions due to mixing Apple ID's across different functions on the device. This is not how it was intended to be used.

[Edited by Moderator]

Yep, that user has now lost the ability to update any of their apps without specifically entering the Apple ID/Password of the previous account that was signed in. Also any new apps they download will now be linked to the fake Apple ID. They thought they created a workaround, but actually just created a mess where they are likely to lose important data by getting locked out.