Schengen visa: Do I need to submit friend's invitation letter for 2-day visit during 10-day trip within Schengen Area?

Question

I'm a Vietnamese passport holder so I need to apply for visa to enter Schengen area this October. The main purpose of my trip is to join company training in Belgium with Brussels to be my port of entry. However since I'd be arriving early Friday, I'd like to fly to Oslo to visit my friend over the weekend first and will stay at her place before actually joining the training in following week.

My questions are: (1) Does my friend need to provide me with an invitation letter with her signature and confirmation from local authority on her residency status there? (2) Will she need to mail the paperwork to me in Vietnam?
(3) Does she need to send along copy of her passport, visa and proof of ownership of the property? My friend is Vietnamese, has lived in Oslo for 5 years and now works there under skilled worker visa. She also owns the place that I would be staying (bought it with her Vietnamese husband, still paying mortgage installment).

For 2-day visit, I really don't want her to skip work and go to local office for such hassle. If having such invitation letter is a must, is there any other alternative option for me to prove my accommodation during my trip to Oslo? (Maybe book then cancel the hostel booking? I'm not sure if it's OK to do so).

TIA :)

Answer 1

The justification for your sojourn in the Schengen Area is company training. You do plan to also visit a friend, but that is not why you are travelling. You are going on a business trip and should apply for a business visa.

Documents to be submitted for a business visa from Vietnam to Belgium do not include proof of accommodation, unlike for a family/friend visit visa. Your friend does not need to submit anything.

As there is nothing suspicious or illegal about visiting friends or family while on a business trip, there is no reason not to answer truthfully to any questions about this side trip.

Answer 2

As long as you have the visa for your company trip, your friend doesn't need to do anything. Just following the procedure to get the visa for that biz trip, and you're free to visit your friends wherever they're in Schengen area.