I am currently working in Switzerland on work permit and my parents obtained a Schengen Visa for travel which has a validity of 90 days. In the visa, the duration of stay is mentioned to be 55 days - this is same as the original itinerary of the travel.
Now that they are in Switzerland for last 40 days - I wish to extend their stay for couple of more weeks which would result in their duration of day as 75 days (which is more than 55 days but well within 90 days of validity).
Could anyone please suggest if I would need a formal approval process from local canton or national immigration office?