...documents regarding the maintenance of three children by the husband, there was one ambiguity. It is given: a family, three minor children, living in the same family, but one child of the wife from the first marriage. The biological father of this child does not pay alimony, because in the case of a divorce the wife did not file a lawsuit to collect alimony from her ex-husband. From the documents: marriage certificate, birth certificates of all three children, certificate of a large family.
What documents can be used to establish or confirm the maintenance of an illegitimate child? Which body, in general, issues such certificates?