Cascading Date Parameter

[whitmore]

I have a parameter which allows the user to select from the following date options:
Last 12 Months
Current Year
Last Year
Current Quarter
Last Quarter

These are working fine. I would like to add another choice called Custom Date. When that date option is chosen, I would like for the user to be able to select a start date and end date. I would prefer for those paramaters not to be visible when selecting any of the other option. Is there anything in Reporting Services which will help me to do this? It sort of like a cascading parameter but not really.

Thanks for your help.