It would indeed be wonderful if the princesses would get involved in NL DOET as well. This year is the 20th anniversary of the event, so that would be a great moment to start. There are various activities over the weekend, so it should be possible for them to join one of them for a few hours.
However, of course Alexia is on her gap year so could be anywhere in the world and Amalia's presence would require a lot of security presence; Ariane is still under age and at school in Italy. So, while I hope Amalia and Alexia show up somewhere, I don't keep my hopes up too high.
Nonetheless, I do expect some other family members to show up at various activities over the weekend.