Co-op (Divinity: Original Sin 2)

I have a question. I'm playing in a co-op. Responsibilities are divided. I do crafting and stealing. It's long and tedious for two. Or you have to replay some point, and he's busy. A comrade can't sit in a game while I'm stealing. Can I play only my two characters for crafting without his participation, or can I play all four characters?? I understand that his computer must be turned on for this?