Query to populate list boxes based on multiple form controls

[gwoman]

I have a combobox and 2 listboxes on my form and a datasheet view of the table that these are populating. I am having a problem creating a query to populate the listboxes. On the afterupdate event of my combobox I call a query that populates listbox1 with all the items relative to the combobox item selected. I need to create a query that checks the combobox itemselected ID & the items related ID's in listbox1 to see if they exist within the table. If the combination of the cboboxID and the lstboxID exist in the table then that specific related item is displayed in listbox2 & no longer is displayed in listbox1.
My problem may very well be that I am making it more complicated then it really is....
Anyone have s suggestion?
Thanks!
gwoman