I'm actually working on a story based on this prompt (and yo, it is difficult; I think there are advantages to poetry, there!).

There's evidence in Komarr that children are always under the control of some male relative in the absence of a specific legal document stating otherwise--it's even observed on Komarr, which is why Nikki's treatment proved difficult.

So the question would really be whether an unmarried female would be classed the same way, as a child. (Ick, I know. But not that uncommon in some parts.) Or whether Pierre would have put some kind of legal protection in place for Donna; unlikely, since he was so sloppy about failing to name an heir.