Some juveniles share the mother's burrow, help her drag prey into the burrow and share her food. Others build chambers inside termite mounds and live together in a community, or hibernate in groups during the winter. These examples came from Gordon Ramel 's page which has lots more details of such communal and parental behaviour. The babies then climb onto their backs. Other mums position their legs so the babies can climb up quickly.
Most mothers can recognise their own babies by smell and pick up fallen babies.
Babies don't survive if they fall off. Besides protecting the babies from predators, some suggest that staying on her hairy back actually provides babies with a more conducive moist micro-climate. Some mothers may actually transfer water through their skin to their babies. Before their first moult, the babies don't eat and instead subsist on the egg yolk in their mid-gut. Soon after their first moult, the babies drop off from their mothers' backs and are able to feed on their own.