Adding winter units to missions

[yannara 0]

I try to setup multiplayer gaming (host and/or dedi) on Chernarus Winter. The problem is, that in every mission style (escape, dynamic recon) all units still have summer clothes. In Antistasi, I managed to pick up artic units which have winter clothes, but all civilians are still running in summer shorts. Someone gave me a hint, that I could edit mission file and add units there but I have 0 skills in editing. Is there an easy way to do this trick? I had basic experience 20 years ago to create simple missions in Operation Flashpoint without scripting, but now new tools look very unfamiliar to me. I tried to google this but couldn't find anything.