so if you want to have a series of subdomains (not sure why)
you can add
nc.foo.ddns.net
bw.foo.ddns.net
bl.foo.ddns.net
to your /etc/hosts file pointing to your internal ip address
have your family also edit their own host entries on their own systems to match what you have.
Not sure about nginx but apache I would add virtual hosts for each of the names with a different docroot pointing to different parts of the webserver
seems like a lot of work for not much benefit but I am not sure of what problem you are trying to solve
you can add
nc.foo.ddns.net
bw.foo.ddns.net
bl.foo.ddns.net
to your /etc/hosts file pointing to your internal ip address
have your family also edit their own host entries on their own systems to match what you have.
Not sure about nginx but apache I would add virtual hosts for each of the names with a different docroot pointing to different parts of the webserver
seems like a lot of work for not much benefit but I am not sure of what problem you are trying to solve