Hi,

I guess, you can't inherit manifest. But what you can do is that in your module write in the ir.module.module object. Thus, a plan should be:

1. develop a special module which depends on 'base' only with 'auto_install': true

2. in this module introduce a pre_init_hook, where search for required ir.module.module objects. E.g. by technical name = 'website'

3. write in this object required data. E.g. object.auto_install = True

I think, the final behavior would be smth like:

1. you create a database > 'base' is installed > you app is installed

2. pre_init hook is launched > other modules are updated

3. the required modules are auto installed.

Potential troubles:

1. when you updated the list of apps, the changes would be lost

2. when you installed the app, there could be some changes
   

My advise: much simplier is to make customization right in the core. Although it is not a good idea as well, at least it would work in 100% cases