How do i link to groups from a drop down list in an excel workbook

hello...
Is it possible for one to link three different groups from a drop down list.If so, here is a brief explanation of what i hope to achieve. I have three drop down lists.one with four districts in each.each district has thier own teams which are broken down to unit level.when i pick a district from a drop down menu i want the teams and unit in that district to appear without having having to manually select them each time i pick a district.I hope that makes sense.
thanks in advance..
fodeps

Can you provide a copy of, or example of, the file to look at?