if you have another valid ticket for the first leg just doesn´t add it to your pass as you use it without the railpass

Hey Seewulf thank you for your reply! I only have a valid ticket until the border - from the border of Switzerland to Paris I need the Interrail pass. However I even if I try to add the journey from the last stop in Switzerland to Paris it wants to count it as an outbound journey… 

yeah the system doesn´t recognise the virtual rail borders best option for you is to log from the first french station of your train

Ah bummer. Thank you :) 

Do you know - if I already add my 3rd and 4th travel day, will I be able to adjust them still after I have embarked on my first day of travel? Thinking of adding my second journey to “use” the outbound journey and only then adding the first trip. 

You can change add your travelday´s at every time but be carefull if you activate them by mistake for the actual day you can´t cancel them anymore same happens if you added your travelday in advance and notice in the morning ohhh no i wanna stay a day longer in this place