Who knows what it was that ended the engagement of prince Gustav and his French Fiancée - there is so much depending on the actual wording of that infamous will. As the Danish court was involved it could have been that queen Margarethe was to "ennoble" the bride or her father, but she didn't want to convert. But obviously the family thought they could work around the will or even fulfill the stipulations with this marriage. But it didn't happen, Richard died and now a court of law has to decide because the potential heirs obviously could not decide in unisono what should happen. That's how I interpret what the lawyer was saying last year. According to what Bunte-magazine wrote last year, Ludwig Ferdinand hopes to be named as new manager of the estate instead of Gustav, for they allegedly wrote that some of Ludwig's daughters is going to move into Berleburg Castle after Gustav moved out. That's the reason why Gustav's lawyer spoke up after all. And he could have a chance because he has the experience to do the job and do it good for the sake of the estate (and the people who work there and are dependant on the princely house). That's the only explanation I have for the question why he should be interested in the estate and even if the will was declared void, he wouldn't be one of the recipients of parts of the estate, because his father was a brother of the 5th Prince and if someone dies without a will, only his children have a right to the estate, but not a nephew.
So the only thing that makes sense is that he wants to become manager of the trust left by his uncle und become custodian of Berleburg. Everything else simply makes no sense. And honestly I can't see why any court should do that as long as there is still the chance that Gustav fulfills the stipulations one day. Stranger things have happened.
Here's the only a bit more in-depth report I could find:
https://www.wp.de/staedte/wittgenst...m-das-erbe-von-prinz-richard-id214989751.html