They combined with their skiing suits. What does it mean?
They were up to no good with their ski suits.
They were cheating with their ski suits.
The verb kombinować is _very_ expressive and has no good equivalent in English*. It implies a mix of guile, improvization and get things done in a not entirely legal or ethical way. The character Rysiek in Miś is a worldclass kombinator and in a sense the whole movie is about the weird extremes people had to go through to get things done that shouldn't be that hard.
It was a necessary skill in the PRL and a family without a kombinator who knew how to get things done and/or find hard to find goods had to made do without.
*at least in the US, maybe the UK has something... I've sometimes heard 'tricky' applied to people but I don't know if it's the same thing