Hi,
It talks about the dependencies among interfaces, zones and routing-instances:
"You can assign one or more logical interfaces to the same zone. You cannot assign a logical interface to more than one zone.
You can also assign one or more logical interfaces to a routing instance . You cannot assign a logical interface to more than one routing instance.
You must also ensure that all of a zone’s logical interfaces are in a single routing instance . Violating any of these restrictions results in configuration errors"