Around here if you add a playground to your restaurant you will immediately get families.
They should keep toys in the back and make the store one big toy playground. Playscape, track for riding bikes and electric cars, sand area, water area, walls of video games etc. Have "lands" similar to disney where those types of toys are available to play with. Have guides to help kids play with toys. Consumable toys can have a charge to use or art classes, science classes, electronics, etc.
Catalogs or computer screens that let you buy the toy and someone brings it from the back.
Parents will bring their kids to play and will end up buying things.