I am still newbie configuring nginx.

Is it posibble to configure multiple domain in one file and they share mostly the same config?
For example I want to configure two domains that based from one app and one domain need basic auth, the other doesn't.
I would like to do something like this, but I think this does not work:

sites-enabled/mysite

server {

    listen 127.0.0.1:80 default_server;
    server_name www.mysite.com;
    include sharedconf.conf;
}


server {
    listen 127.0.0.1:80;
    server_name www.mysite.co.jp;
    auth_basic "restricted";
    auth_basic_user_file /etc/nginx.htpasswd;
    include sharedconf.conf;
}

sharedconf.conf

location / {
    proxy_pass_header Server;
    #... bunch of config line ...

}