revlob

I play on PC. I have recently merged my PC account with my old Switch account I never really used. I believe that makes my account a "cross save" account according to the official page on the new feature. My son plays on Switch (and has no other account). We can play together just fine, but when I try to trade with him I get an message that he must have a cross save account to trade. I'm confused, do I also need to set him up with a PC account in order to trade across platforms? The advice isn't clear, please help, I just want to give him some mods and stuff!