Do only their children have this right?
No, unfortunately only children are entitled to free travel. In addition, there are some peculiarities.
In accordance with Article 13 of the Law "On the Protection of Childhood", children from large families are granted free travel on all types of urban passenger transport (except taxis), public road transport in rural areas, as well as suburban railway and water transport and buses of suburban and intercity routes, including intra-district, intra- and inter-regional, regardless of distance and place of residence, in the presence of a certificate of the established model, and in the case of the introduction of an automated system of accounting for travel payments - also an electronic ticket, which is issued free of charge.