You mean you don't plan to give her a bedroom? I think a maids living space is like anybody elses, it's commonly called a bedroom. If you need a 3 bedroom
condo but want a maid then rent a 4 bedroom condo. Unless, that is, you plan on her sleeping with your kids. Or do you plan on her sleeping on the kitchen floor (it's been done quite often here) or on the porch or in the storeroom (in the case of newer HDB flats with the bombshelter fortified Storerooms)
Or........
Are you thinking of a separate studio apt built into the flat complete with kitchenette & toilet? The only place you will find something like that is in the Old Black & Whites built pre-war. These are not condo's but huge colonial houses with large compounds and even larger price tags. (somewhere around 5 digits/mo.)