Child nodes with multiple parents in a parent-child hierarchy

I'm currently working on building a Finance datamart using Microsoft BI suite. As you may know, one of the key things while working with a Financial application is to understand the Chart Of Accounts(COA) - how a company categorizes their accounts such as Assets, Liabilities, Expeses etc. for the purpose of recording into GL.
The recommended UDM data model for COA is parent-child since it offers a number of benefits such as Custom Order,Custom Rollups, and Custom Members.

One of the limitations of a parent-child hierarchy is that it only allows you to have one hierarchy , which means a child node can have one and only one parent. In real world
this limitation will become an obstacle very quickly. There are a number of ways to design and implement such a requirement. Refer to the articles many-to-many revolution by Mark Russo
and Duplicate members in Analysis Services by Richard Tkachuk