Add Collapsible data to report or form

[Bob]

I want to show a report with the following levels:

Asset Class
Investment Option
Dealer Group

So within each asset class there will be options then within each
option will be dealer groups. Easy enough. Now what I want to do is
somehow show something like this..

[-] Asset Class
[-} Investment Option 1
Dealer Group 1
Dealer Group 2

the [-] are collapsible levels. So I want to initially display all
asset classes and how much is in them, then allow the user to click on
the report, or form and then display underneath the asset classes the
investment options, then the same procedure for the dealer groups
(sorta like excel subtotals I guess). How could I do that? Bear in
mind I do not want to only show one asset class, investment option or
dealer group at a time - all must be visible. I see my options as
being:
1) design a form with datasheets and add commands to the subform that
then show the relevant dealer groups??
2) design a report which has the little plus's and minus's that will
collapse parts of the reports - can you put commands on a report? if
so that sounds viable?
3) export the whole thing to excel and then automate subtotals
somehow?

Please help! If you can suggest something please give me some code
example if time permits.

Cheers,

Bob