When her cousin, the duke Frederick Wilhelm III died childless in 1672, Elisabeth Sophie became in the general heiress of all the branch of Saxe-Altenburg on the basis of her father's testament (as it was ultimately recognized in law that the Salic Law does not prevent an agnate from willing all his possessions to those other agnates of the house he desires to make his heirs, leaving other agnates without; and if those favored agnates also happened to be the testator's son-in-law and maternal grandsons, that's in no way prohibited).