This is incorrect. TBH, I have never understood the point of posting answers one does not know for certain to be true. Is it just to get people to give up and go away instead of trying to help them, or is it for the thrill of acting like you know something they don't? I don't know if you are an Apple employee or just a guy posting stuff, but either way, don't post answers when you don't know. It just aggravates people.
The Apple Music for Android app in fact does have a function set up for adding family members. You are supposed to be able to click the three-dot menu in the upper right corner of the app, then Account, then Manage Family. This, however, is very glitchy, and the only way to get it to work on my phone was to completely uninstall Apple Music and then reinstall it. Apple really should try harder to support its apps and ensure they work.
The real problem, it turns out, was that for some reason when I upgraded the account, it messed up Apple's link to my payment information, so the app kept asking me to verify payment information by entering a code that had supposedly sent to a device, even though it hadn't. (I worked with an Apple tech support person over the phone and she couldn't figure this out either.) Finally, I decided to try deleting and re-entering the payment information. Of course, Apple only lets you delete a card if you add a new one, so I had to enter a second card, delete the first, re-enter the first and delete the second. Kind of a hassle, but it worked.