What is the correct way of overriding hiera in a fuel plugin?

I am writing a plugin to create a second external network for floating IP addresses. The plugin on itself works, it is just a puppet manifest creating a common.yaml file in /etc/hiera/override to override the network parameters.

The problem I ran into is that when I install the stacklight plugin (LMA-toolchain), the deployment fails because of an 'invalid cfg_hash format'

The origin of this error is the fuel-library get_network_role_property function that is called in a couple of the LMA puppet manifests.

So know I am wondering where I should override my hiera file so that the stacklight plugin still works?

Thank you,
Niels