This analysis deals with the different forms of logic that drive a family when it needs to take into consideration both filial and legal obligations. The cases studied deal with situations where the rules of operation laid down by public authorities result in children taking a large number of business decisions on behalf of their lineal ascendants. Purely family arrangements then have to give way to the transparency requirements imposed by the public registry with regard to statements of account. The result is that many children end up by taking over the handling of monetary affairs, of cheques and bankcards. This happens all the more frequently due to the number of warnings issued to elderly people, telling them to be careful and to protect the assets and cash that they keep in their homes. This preoccupation with streamlining and protection embraces the neighbouring safety net of friends and relations, is reinforced by public transparency requirements and takes little account of private values and concerns for confidentiality. In such a context, handicapped people may find themselves deprived of means of exchange and of any way of ensuring that they have enough money left to live on.