When starting or ending constituencies in global changes, we need an option to base the start or end date based on the date the change is run. Ideally, these changes will be scheduled, but without the ability to dynamically set constituency start and end dates, the constituency will get a fixed date regardless of when the change is run. This prevents us from scheduling these changes, since the dates must be manually changed. Also, in addition to the option to overwrite the existing value, we would like options to: - add multiple records for the same constituency (should someone end and then resume their giving at that constituent level) - update an existing matching constituency record with an end date (to keep the start date intact)