Accepted family sharing invite but Apple Music still wants to charge as if new/separate account

Hello mbctga,

You can find this information about how the Apple Music family subscription works at Share Apple Music with Family Sharing on Mac - Apple Support:

When you subscribe to Apple Music or Apple One with a family subscription, you can use Family Sharing to share Apple Music with up to five other family members. Your family group members don’t need to do anything—Apple Music is available to them the first time they open the Music app after your family subscription begins.

Based on what you are seeing, we would confirm that you are part of the Family Sharing group. Tap on Settings. Right below your name you should see, Family. Tap here.

You should now see the members of the Family Sharing group, along with available subscriptions.

If you think everything is set up correctly, and you are not seeing these options, reach out to Apple Support here: Get Support

They will be in the best position to assist further.

Have a good day.