Great, that’s exactly what I was asking in my first question. So, the answer is (2), not (1).
I’m not an accountant, and I’m definitely not an accountant in your company/country, but I’ve never seen a cash flow statement calculated on the basis of payment schedules. It would be relatively straight forward to build such a thing (using a script or query report), but it is not a standard feature of the cash flow report and I wouldn’t expect it ever will be.
It’s possible that there is another report bundled with ERPNext that does what you’re describing, but if it exists I am not aware of it.