If all eight lines are under one account name, and you are the primary account holder, maybe you can pay for it all using autopay, then collect from everyone. That sounds like the most easiest way if you're going to combine eight lines.
Although, please know that if you are the primary account holder, you are financially responsible for paying for those eight lines. If you don't know them close enough, why even do it at all?
Hope that answered your question.
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