@atenger 

As you suggested, you just need to create an expense account called "Guaranteed Payments - Partner X" and use that for the guaranteed payments.  Guaranteed payments are an expense for the partnership and are not subject to withholding.  The payments are reported on Schedule K of the partnership return as well as partner X's K-1. As you're probably aware, you split the partnership income 50/50 after deducting the guaranteed payouts.