Can you get secondhand chickenpox?

I was supposed to take my grandmother and cousin out to get school clothes tomorrow with my 17 month old son. My grandma just texted me and said my other cousin came to their house and told them how his son had chickenpox.

Obviously I’m debating wether or not I should cancel tomorrow’s plans because I don’t want my son sick and I’m very very pregnant too. Could my son get the virus by being around family who wasn’t in direct contact?