Hi Alok,
the customizing for the 'early repayment' functionality is in the IMG, flow type customizing for the decrease: set the flag 'Accrued Int. Calc with Capital Reduction', SEARLYREP.
But I don't think that you will get the expected cash flow - is this really what you want to achieve?
Is there really no interest in the period from 01.04.2012 up to 31.07.2013?
Without the SEARLYREP, you will get two flows:
1) 01.04.2012 up to 31.07.2012: based on 60M
2 )01.08.2012 up to 31.03.2013: based on 40M
With SEARLYREP:
1) 01.04.2012 up to 31.03.2012: based on 60M
2 )01.08.2013 up to 31.03.2013: flow in different direction based on 20M.
Hope this helps,
Marie