"И Дима, и Вера — их дети."
Translation:Both Dima and Vera are their children.
Did you not above agree with ChemaxSidd who wrote, "It seems to me that simply saying: 'Dima and Vera are their kids' is sufficient in this situation."?
As for why I entered an answer without "both" myself before seeing this discussion, it was out of curiosity to find out whether it would be accepted or not. I would not have submitted a report if I hadn't seen your post above.
I assume you meant that "Dima and Vera are both their kids" would be acceptable, but that wasn't what ChemaxSidd asked.
Thanks for all your work on this course, it's fantastic :)