One.template.instantiate issues with networking

We are using the XML API to create a new VM using one.template.instantiate
during the call we are adding value to the Context of the VM.

When we do this the network information is not being fed to the context from the template, it seems that when we add to the context using the API it removes the template context all together rather then merging it like the documentation is saying it will do.

with that being said does anyone have a recommendation on how to add the network information to the system after it has been instantiated or should we be using a different approach all together.

The main reason we are overriding the context is setting the root password and running custom startup scripts that are dynamically changed so that can not be stored in the template itself.

**Versions of the related components and OS : CentOS7 - KVM ON 5.6.1