"František je rád, že jeho manželka je Němka."

Translation: František is glad that his wife is German.

[fehrerdef]

"svá manželka"?

[VladaFu]

No, that is not possible. The subject of the sentence is "jeho manželka", not "Tim".

"Svůj" only relates to the subject of the current sentence. The sentence is subordinate, but it still is a sentence: "(že) jeho manželka je Němka. "