FactoryTalk View, like Time itself, only progresses in the forward direction.
It is not possible to edit a FactoryTalk View SE 7.0 system using FactoryTalk View SE 5.10 software.
When I was still working with FactoryTalk View SE, I created a VM with only the specific version and patches that each customer was using.
It might be possible to export and import individual *.GFX files (which define each Display) but I would not be surprised if you ran into bugs or problems when attempting to go between major versions.
If your customer has FactoryTalk View SE 7.0, you should be using the same version to perform work for him.