overnight train

No only as one.

Night train rule goes as follows:

When travelling on a night train, you only have to write down/register the day of departure. For example, if you travel on a night train from 9 to 10 August, you only write down 9 August. If you're travelling with a mobile Pass, this will happen automatically once you add the journey to My Trip.

On the day of departure of the night train, you can take as many trains as you want; it's on the same day after all. If you take another train after the night train has arrived, you'll have to use a new travel day.