Way to populate data for current quater months from last month of previous quater

Hi  I have a requirement to load forecast data into the SSAS cube.

My current data:

Snapshot_M       Date         F_Quantities

1/1/2014        1/1/2014    100

2/1/2014        2/1/2014    90

3/1/2014        3/1/2014    80

4/1/2014        4/1/2014    23
4/1/2014        5/1/2014    0
4/1/2014        6/1/2014    0

I want this two be shown as

Snapshot_M       Date        F_Quantities

1/1/2014        2/1/2014    100

1/1/2014        3/1/2014    100

1/1/2014        4/1/2014    100

4/1/2014        5/1/2014     23
4/1/2014        6/1/2014     23
4/1/2014        7/1/2014     23

Snapshot_M filed is the month when data was loaded.

So to summarize, the data that is loaded in last month of fiscal Q1  (January) should serve as data for fiscal Q2 (Feb, Mar, APR), the data loaded on last month of Fiscal Q2 will serve as forecast data for Q3 an so on. ...

Thanks