[Resolved] Use of subdomain can bypass login on main domain

I’m trying to create a Family Genealogy Site. I was pleased with how the plugin worked on the main domain. Then I needed subdomains to accommodate and manage a large number of family branches and images. When testing security, I discovered I could access the subdomain independently and from there enter the main domain without logging in. I actually need several subdomains to deal with the many family branches. Is there a way to prevent entry into the subdomains except via the main domain which is password protected?