98SE+Office 2000 / Excel Question

Hi all, I have an Workbook with 24 Worksheets.
The first three are the major ones and the other 21 contain
details of the three major ones.
At present, all links to the 24 Worksheets are spread across the
links bar at the bottom of the window.
I would like eg major Worksheet 1 to be a folder that contains it's subworksheets 5, 7, 12 and 18.
Major Worksheet 2 would also be a folder containing Worksheets 4, 6, 8, 9, 11.
And so on ..
I cannot find a way to group Worksheets into such folders ?
Any help most appreciated.
regards