NPV Formula Using Uneven, Monthly Cash Flows

Background: We're doing our annual valuation work for a portfolio or real estate assets.

Problem: The projected cash flows come in monthly intervals, and have multiple outlays (negative values) in both months one and two.

Question: I am using =NPV(rate/12,range)+IO. Does this formula suffice for a series of cash flows with multiple outlays (more than just the initial month-one outlay I add back in the formula)? I suspect not, but don't know how to correct for this problem.

The attached spreadsheet should further illustrate my question. Any guidance would be very much appreciated!

The NPV formula above will work just fine afterall. No need to account differently for multiple outlays.