SAP BW, AP ageing report. Net Due Date calculation logic

Initial design of ageing report in BW built so that open items are analyzed based on due date field. 
And when partial clearing of invoice is happening, because of the due date of partial clearing document (BLART=SC normally), open items value periods- wise is getting incorrectly displayed, i.e. it is not getting decreased at all.
So idea here is to have equal due date both of SC typed document and of original invoice (KZ, KR, and etc. etc. typed documents).  
Net Due Date field (BSEG-ZFBDT) is not controlled with fields status group, it is controlled with APP configuration t-code, i.e. FBZP. 
In order to activate Net Due Date for AP clearing documents it is necessary to add spec. G/L indicator 'A' into vendors tab in FBZP (All company codes section). 
And then with explicit enhancement you will have to:

(1) block clearing documents for APP run (once you added spec. G/L indicator, partial payment documents ,having the indicator, will be selected to APP); 
(2) update BSEG-ZFBDT of clearing document, getting generated with F-44 t-code. 

Net Due Date logic is as below (if you tried dealing with Net Due Date, you might notice that this date is getting calculated from several fields, depending on payment terms): 

Net Due Date= BSEG-ZFBDT+ BSEG-ZBD1T
if else BSEG-ZBD2T>0 then Net Due Date= BSEG-ZFBDT+BSEG-ZBD2T

BTE for updating BSEG-ZFBDT from F-44 is 00001130.
Standard FM for BSEG-ZFBDT in F-44 is SAMPLE_PROCESS_00001130.

So after Net Due Date of clearing document is getting updated with Net Due Date of original invoice, then BW Ageing report will be displaying correct dynamic of open items periods- wise. Et voila! :)