Currently our cache helpers do not cater for the case where a mutations returning multiple nested relationships could be returned.

This is naive and should be fixed. Two possible approaches:

1. We extend the interface so that the developer can provide each query in turn and the cache helpers will then generate these update functions. Not ideal but means we can support this feature easily.
2. We extend the helpers and implement a nested and recursive approach. There is a lot more work in this option.