Dynamic Date selection using cascading source in cognos 10

[chinnucognos]

Hi All,

i have a requirement as below,

End user must be able to select from a dropdown list a year value.
After selecting the year value the end user must be able to select from a dropdown list a quarter value.
Year value: PY1, PY2,PY3,PY4,PY5 etc.
Quarter Values:
QTR1 – July 1 – Sep 30
QTR2 – Oct 1 – Dec 31
QTR3 – Jan – Mar 31
QTR4 – Apr 1 – Jun 30

If selected year values '2014', we Must exclude transactions in the posted items file, based on the field "Transaction Date" with a date value less than May 21, 2014.
if we select 2015, Q1 data should be between July 1 – Sep 30
where as if it's 2014, data should be between May 21, 2014 - Sep 30 
we have to use cascading source for this, but the problem here. we are using 'the same date column in both cases
and the data type is datetime

please help me in getting this logic. and this is high priority logic for us