"Bereme si její bratry."

[Renardo11]

This seems a pretty complex lesson. So is “bereme si” = “we are marrying other people”, and “bereme se” = “we are marrying each other” = “we are getting married?”

I wonder if I will ever get to apply that knowledge in practice…

[DaanBanaan18]

This link might help you.
https://forum.duolingo.com/comment/24689285

For 'brát si' you require an object basically and for 'brát se' you are talking about the act of marriage itself (but you can still specify with whom using the instrumental case).

This dictionary is also useful.

https://www.nechybujte.cz/slovnik-soucasne-cestiny/br%C3%A1t?

[BoneheadBass]

Thanks for the pointer to this dictionary. I'm always happy to have another resource!

[BoneheadBass]

Looks like you're doing pretty well with this!

[Renardo11]

Thanks, but I have been trying to learn Czech for 25 years now, with different courses, and I had never come across this before… but that's a different story. I take it that my conclusion was right, and that “bereme si” can also be used more generally, similar to “dáme si (kávu, čaj).”

[BoneheadBass]

I don't know how authoritative/accurate/useful it is, but you might have a look at this site for examples of other ways "brát si" is being used out there:

https://glosbe.com/cs/en/br%C3%A1t%20si