Duplicate scenes

As the others mentioned, the problem is that duplicating a comp does not duplicate any precomps it is using and also not any footage items. YOu can either use third party tools like True Comp Duplicator to create deep copies or create an empty project and then import your template project into it several times. That way, with each new import of your template you effectively get an entire, indepentend copy of the template project, each in a separate folder of your project.

Insert a template and then duplicate the footage in the project panel for each friend/family you need to insert into your composition. Otherwise you will be editing instances of the master and every time you edit an instance all will be modified.

Are there precomps within the template? If so you'll want to duplicate these as well. Make sure in your project finder that you have separate folders for each scene you want to make.