You can import whitelist NoScript rules. Go to the My rules pane in uMatrix's dashboard, then click Import from file.... You can select a NoScript backup file and uMatrix will import what it can from the backup file. The imported rules will apply to the script column of the global scope only.

You can import whitelist RequestPolicy rules. Go to the My rules pane in uMatrix's dashboard, then click Import from file.... You can select a RequestPolicy backup file and uMatrix will import what it can from the backup file.