From Belgium to Schenzhen, from Schenzhen to Hong Kong. Spending 10 days in Hong Kong then come back

Hi all,

I am currently a Belgian expat living in Hong Kong. I have friends coming to visit me in Hong Kong end of October. However, their plane only land in Schenzhen (it was cheaper than landing in HK) and their goal is to directly go to HK and spend the 10 days there. Afterwards, they go back to Schenzhen to take their plane back.

I suppose they don't have to apply for a full Chinese visa (which cost quite a lot)? Can they apply for the 5 days Schenzhen VOA when they arrive in Shenzhen and then go directly to HK? How about when they come back to Schenzhen to take their plane back to Belgium? Will they have to apply for another 5 days just to be able to reach their plane?

Thanks a lot in advance!! Cheers

Pierre