You might have to put the quail eggs in a bowl just big enough for the bantam to sit in (hide it under the bedding so she doesn't notice) and add a few chicken eggs or fake chicken eggs too because often they don't recognise the quail eggs as eggs. I have used a bantam before but the babies definitely need to be brooded by you. Quail are a lot more helpless than chicken chicks, needing to eat sooner (within the first 24 hours), needing to cuddle more, and a hen just doesn't understand and goes about her business as if she has 'normal' chicks.