A more thorough explanation:

Droit d'accroissement is a legal term in French law that refers to a right of survivorship. This means that if one heir is unable or unwilling to accept their share of an inheritance, their share will be combined with the share of another coheir.

For example, let's say that a father passes away and leaves his estate to his two children, Marie and Pierre. However, Pierre decides that he does not want to accept his share of the inheritance. In this case, Marie would have the right of survivorship or droit d'accroissement, which means that she would inherit the entire estate.

Another example could be if a grandparent leaves their estate to their three grandchildren, but one of them passes away before the grandparent. In this case, the droit d'accroissement would come into play, and the shares of the deceased grandchild would be divided equally among the remaining two grandchildren.

The examples illustrate how the droit d'accroissement works in practice. It is a legal mechanism that ensures that the inheritance is distributed fairly among the heirs, even if one of them is unable or unwilling to accept their share. The right of survivorship is a common feature of inheritance law in many countries, including France.