Joseph, a goy’s son inherits him mi d’Oraita so if he has a son it is now his. If not, it goes according to secular law (Rambam, Hilchot Nachalot 6,9).
Rebbetzin, you may have a problem. Even if there is a clause requiring him to pay by a certain time it might be an oness that stops the clock. This is a sugiya regarding a conditional gett (Gittin 30a). Ask your LOR.