If you are considering installing a 3rdparty plugin on your NRO website, first read our relevant guide around Plugins, espcially the part about the Security review. The Planet 4 team can help with perfoming a security review.
If you are adding a plugin you developed then make sure you have read our guide on how to add it to Packagist.
To add a plugin for only one NRO website, you need to do the following steps:
Have access to that nro site controlling repository (eg. GP Netherlands)
On the develop branch, on the file composer-local.json, in the
require block, add a line that will reference your plugin from packagist (for own developed plugins) or wpackagist (for 3rd party wordpress plugins).
For own developed plugins, please note that the version can be one of the following:
A tagged release (for example: v1.0). Mandatory for production releases.
A branch name.
Commit. This will trigger your dev site to be rebuild including the new plugin.