Are her messages to you through eBay on record showing she is trying to change her address to another country? You need a paper trail to protect you. I would make sure all messages are done through eBay and would tell her in any personal emails to you they she needs to go through eBay messages.
This is where my lack of knowledge comes in because Im not sure if the messages are going through the case.
When I open up the case there is a "contact seller" option which is just a regular message, but the headline says: "Return: so and so send a message".
But the case itself doesnt have like a "wall" where you can post comments.
Hope this makes any sence.