"There are seven people in their family."

Translation: उनके परिवार में सात लोग हैं।

[AadishRahm]

why is उनके used instead of unka?

[another-dave]

At a guess (also a beginner), I'd say it's because when we add में as a postposition to "their family" it puts it in the oblique case

[Maheshwara19]

Can we use "unhe" instead of unke?