Patches not executed on new site

How come patches are not executed on new site ?

Here is the scenario:

1- I have multiple sites running.
2- New development - I create a new doctype and want to seed default data into this doctype.
3- I install a new site

How can I seed default data for both existing and new installations?

As stated, patches won’t run on new site.
after_install hook won’t run on existing site.
Fixtures can’t be use because this is only default data that can be changed by the client, so subsequent migrate must not alter existing data.

check this if it helps Database patch is not applied during install-app - #2 by revant_one

How fixtures can be used to sync data only once?
This is default data for a new doctype. Once installed it can be changed by the user, it must not be kept in sync with fixtures on each subsequent migrate.