Could "małżeństwo" be used for "wedding" too?
Nope, wedding is "ślub", which also means 'vow'.
The multiple-choice version of this question offers the option `Wasi małżeństwo' but doesn't accept it. What's the grammatical issue with that option?
Małżeństwo is singular and neuter. "wasi" is for masculine personal plural.
Can't it be: "Twój małżeństwo"? Instead of "Wasze...."
Twoje. Tak. I said nothing