TIMESTAMPADD - needed for filter

Hi

So we have a client asking this question:

" I am looking for a way to retrieve the last 8 weeks but instead should start from two weeks back from the current week, and then 8 weeks back. Our SLA for certain records takes a full two weeks to determine if the SLA will be achieved or missed. "

"The filter is being applied as a column filter, and the field being filtered is [Week], in case this makes a difference. "

I tried this for them   :  

TIMESTAMPADD(SQL_TSI_WEEK, -8, (TIMESTAMPADD(SQL_TSI_WEEK,-2,CURRENT_DATE)))  - first SQL expression.  2nd Expression in the same filter I just used CURRENT_DATE.  I didn't see a CURRENT_WEEK as an option.