The daughters of sultans were generally married to important political figures in the empire. Leslie Peirce's Beyond Harem Walls explores the role of Ottoman princesses in the context of harem power. "The most important links with centers of power outside the palace were forged by harem women through marriages of daughters, the princesses of the dynasty, to leading statesmen."

The groom of these women, known as damad, generally experienced significant benefit from these marriages and often served as grand viziers. They were still slaves of the sultan, though, and could be executed or dismissed as the sultan saw fit.

Serial marriage of these princesses strictly for political purposes was not unknown, even when we'll past child bearing age. Ahmed I's daughter Fatma was 61 at her last betrothal. Her father died in 1617, but she and her sisters remained political tools until their own deaths in the latter half of the 17th century.

These princesses, once married off, were generally permitted access to their palace home even after marriage their knowledge and influence outside the harem played a part in power struggles between the Valide Sultan and their own mothers.

Edit: typos. I'm typing on a phone.