It depends. If your Journey Guide shows that your Eurostar leg needs to be added to your Pass, then yes - please make sure to add this journey in the app.
If you are using your Pass for the Eurostar leg, your Eurostar tickets are actually Interrail/Eurail seat reservation documents (even though they look like standard full fare tickets!). One of the conditions of travel is that you also hold a valid Interrail Pass with this journey added and activated.
At the Eurostar terminal, barriers and staff usually focus on checking the seat reservation document, so they may not always ask to see your Interrail Pass. That said, checks can happen, so it’s important to make sure the journey is correctly added to your Pass to avoid any issues.
If you will be travelling on a full-fare ticket we will also note this in your Journey Guide and you should not add this journey to your Pass. Your full-fare tickets will be attached to your guide.
