Ginger from the Bratz Kidz Sleepover movie is actually the ghost of Gran from the CGI Bratz Babyz movies.
Their houses look exactly the same. Sure, it's more than likely just lazy model reusage, buuuuut let's admit in Babyz Gran looked really old so I wouldn't be surprised if she died somewhere around the time the Bratz turned 12 if not earlier. Also, last I checked some ghosts are capable of shapeshifting. Or alternatively... Ginger and her family tragically died at the old movie theater she met Sasha at.
Why else would that all be brought up at the beginning?