How to insert base project into child projects?


I would like to know if this is possible (should be?). :)

We currently have Yii2 base project (we can say, like, project root from which we will create other projects). Right now there are several modules, models, controllers and viewers. Everything is fine here but how to deploy (and where) so that when we update base project, all child projects that were using our base project would be updated (best is through Composer with composer update).

For example, Kartik has its plugins/widgets and we can simply update through Composer with command like $ php composer.phar require kartik-v/yii2-grid "@dev".

So we want to have something similar, but not accessible publicly (so that random people couldn’t access without some sort of email/username/password). This part is not as important as the first part because in this part we at least can use something like BitBucket.