Countess Palatine Margaret of Mosbach

At the time of his accession Philip the Younger was only four years old. This situation presented the Hanau family with a dilemma:

• They could obey the primogeniture rule, which had been observed in Hanau since 1375. This would mean hoping that Philip the younger would live to an adult age, marry and have children, who would continue the dynasty. This would have the advantage that all of the family's possessions would remain in a single hand. It would entail the risk that the dynasty might die out, if Philip the Younger were to die without a male heir.
• Alternatively, the famlity could ignore the primogeniture decision and allowed the next agnate, Philip the Elder, to marry. This would have the advantage of significantly increasing the probability that the dynasty continued to exist, but the disadvantage that the county would have to be divided. This model also called for urgent action, as Philip the Elder was almost 40 years old, which was considered quite an advanced age in the 15th century. However, in this model, he would have to have his own territory, because a mere apanage, that is, a financial arrangement without sovereignty, as was practiced in early modern times, was still unthinkable in the 15th century.

In this debate, Margaret favoured the primogeniture solution, in which her son would inherit the whole county. Her father supported her. Catherine of Nassau-Beilstein, her mother-in-law, supported a division, as she wanted the dynasty to continue, but was indifferent s to whether this would happen via her grandson Philip the Younger or via her younger son Philip the Elder. She knew that Philip the Elder was capable of having a son (he already had an illegitimate son at that time) and she didn't want to be the continued existence of the dynasty on her four your old grandson. She managed to convince most of her relatives, and some or the more important organizations among the county's subjects, including the four cities of Hanau, Windecken, Babenhausen and Steinau, as well as her grandson's vassals.

Nevertheless, Margaret had her way. Catherine couldn't implement her plan until after Margaret died in 1457. In January 1458, a family pact was sealed, in which Philip the Elder received the parts of the county south of the river Main, i.e. the districts of Babenhausen and Schaafheim and Hanau's share of Umstadt. The pact also gave Philip the Elder permission to marry, which he did later that year.