how to refresh iframe contents with new url on textchanged of dropdownlist

Hi, Hope someone can help with the following. On my page i have an iframe that displays a page when the user clicks one of the dynamically added hyperlinks which make up the navigation menu for my site. the complication comes with the requirement for "scope" filters: These are a series of drop down lists that the user can use to filter the results displayed in the iframe. So if a grid is displayed initially with the asset list for every work location under our control they can change a drop down to site a and the grid in the iframe should refresh and ddisplay only the results for location A. The drop downs exist on the page outside the iframe as does the navigation menu. i have a routine called which does this, so when the postback from changing the dropdown occurs the new parameters for scope are appended to all the urls of the dynamically added hyperlinks so the next time they are clicked the iframe opens with the correct results. But herein lies the problem, how ...