change combobox values one by one based on selection in multiselect listbox

Hello,

In a UserFrom I have three ComboBoxes to select Chart Type, Month and
Location
I have the code to run at the change event to select appropriate chart
type, month and location.

Now I am trying to make PowerPoint slide from these charts according to
selection.
For that purpose I have three multiselect listboxes for chart type,
month and location.

I have the code to copy three charts (different Chart sheets) to a
PowerPoint presentation.

Based on the selection in the listboxes how I can automatically run the
change event in the three comboboxes and make the charts and copy them
to PowerPoint?

(change combobox values one by one based on selection in multiselect
listbox)

Thanks