Cinderella : Why did the Grand Duke want the Princess of Chelina?

What difference did it make to the Grand Duke who the Prince married? What gave him the right to offer the Princess a marriage anyway? Wasn't it a choice for the Prince to make?

back in the day arraigned marriages weren't uncommon. He mostly did it for some sort of political gain.

He might have some sort of hidden deal with Zaragoza or was just more concerned with the Kingdom.

At the time, arranged marriages were the common way in which royalty wed, and Spanish kingdoms were powerful and rich. Spanish Princesses were popular to wed all over Europe because of their enormous dowries and - most importantly - the strong alliances, which meant the following:
Let's say a British king had a princess of Aragon for a wife. In case of a war with, for example, France, England could surely count on Aragon's Alliance and support in a war. (let's keep Henry VIII out of this- he made a major faux-pas ruling-wise when he broke off with his Spanish queen and the Catholic Church, leaving him with no support from Aragon whatsoever)

Unfortunately they did not stress this fact in the film, making it hard to understand why the Grand Duke was stressing so hard for the prince to marry princess Chelina.

Carolina_1992, I love this comment and you are correct.

Well keep in mind that there technically was no "Spanish" princess in the film. All the kingdoms were fictional. But obvious yes she was supposed to be Spanish or Mediterranean or something.

Actually, all the kingdoms mentioned in the film were real a long time ago. Most of them don't exist now, but Zaragosa was a real kingdom many centuries ago.

And would have probably lasted longer if Chelina married Kit.