RAP's Amounts Delimiting

Hello Experts,

How to create a RAP amount in table V_T7INA9 with two validity periods with different amounts for the same wagetype?

we are maintaining a RAP amount for one wagetype which is defaulting in IT0008. now we had a increment on existing RAP amount.

when i tried to delimit the existing RAP amount, it is asking only Start date. so i given the start date as incremented RAP amount with effective date and changed amount of wagetype and saved. now it replaced the previous amount with new amount and no history was maintained. in IT0008 also the previous amount was replaced with new amount even the Infotype record was past dated than the RAP amount date which created in table V_T7INA9.

so i need the amount of wagetype ABCD in RAP table with two different amounts in two different periods with same allowance grouping.

i.e wagetype ABCD has amount of 1000 from 01.04.2012 to 31.03.2013

                   ABCD has amount of 2000 from 01.04.2013 to 31.12.9999

please help me to create above records in table V_T7INA9 in order to maintain a history in IT0008.

Thanks in Advance.