Have the RowSource for your Building based on the Jurisdiction Combobox, and requery it when Building is changed.
For example, on the AfterUpdate event of the Jurisdiction Combobox (named cJurisdiction here)
Me.cBuilding.RowSource = "SELECT * FROM tblBuilding WHERE JurisdictionID = " & Me.cJurisdiction
There's more elegant ways to do it, but that's the best way I can describe it using code only, and at this time of the day
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