The couple started as small entrepreneurs in the nearby village, doing wholesale and retail, as most of such businesses did at the time. They had a couple of small supermarkets and then moved to larger stuff. At some point they rent a large metal products plant and adapted it into a department store, plus a fancy restaurant.
Then they divorced and split the company. He practically vanished from the picture, while she got some space at a good location in Koče Kolarova, very close to downtown, with offices in the attic and a restaurant downstairs (though I don't know if it was hers or she rent it to someone; there's another restaurant now in that place, with completely engrbian setup)... then another restaurant and now a bakery (ran by Nina's classmate). She stayed a DBA customer. She hired Ćola and Bjanka from under Gargamel's nose, the typical disgruntled employees... as if he ever had any other kind.