If a person wanted to remarry after becoming a widow(er), they first had to come to an arrangement with the children of the prior marriage. These arrangement are often registered in court records, orphan chamber records, or notarial records, often around the time of the publication of the banns of the second marriage.
They can provide a wealth of information about family members and the economic circumstances. See the article about the parents of Aleid Laureijs Coolen. A receipt for her wedding dress in the guardianship papers drawn up because of her mother’s second marriage helped prove the identity of her parents.