I got an email asking if Queen Marie's children married into any Hungarian royalty.
Here's the quick details:
Carol II: Married a cousin int eh Greek Royal Family, but also married a Romanian Noblewoman.
Elizabeth: Married King George II of Greece.
Marie: Married King Alexander of Yugoslavia.
Nicholas: Married a woman of Romanian origin.
Illena: Married an Archduke of Austria.
Mircea: died at the age of Three.
So as for the Romania family there, the connection of Hungary and Romania is not there, but there is a lot of Ties with Transylvania and Queen Marie.