Hello @Tin18 

It's been some time since this post but for you, and for others like me that still can't believe that QBO has so abundant and outrageous limitations like this one, I have this answer. 

Yes, you can create other accounts, children or siblings, but they are virtually useless. You can't select them in any invoice you enter or check that you issue. You can use them only in journal entries.

Below is a limited workaround that may work in some cases. Here is the link: Solved: Re: Multiple Accounts Payable and Accounts Receivable in QBO (intuit.com)

This workaround will not allow you to do what you, and me, would like to do, but it may help with reports if your entities (customers/vendors) can be discretely classified.