Add multiple menu items to a designated parent menu item

Hi,

I must be missing something basic. How can I add multiple menu items to a designated parent menu item? I have like 90 stores I would like to add to a level 2 “Stores” sub menu item. I could add them all to the menu with the “Add to menu” button, they ending up at the bottom of the menu item listing at level 1, but I would then have to drag and drop every single item to its correct position at level 3 under “Stores”. Tedious. Hints? Custom plugin? I have searched some but can’t find a solution.