I think I put several of my models into the Menschaar Collection at the American Merchant Marine Museum. Fritz had a complete set that was dismembered during the post humus auction. Originally, I bought his extra WWII Nieuw Amsterdam from him in 2000. He knew Robert de Vlam very well and ordered models directly for me. In 2010, I obtained a WWII Nieuw Amsterdam on ebay.de (1:1250 Noordzee Schiffsmodelle) for a US collector; it may have been for your brother 😊
https://photos.app.goo.gl/fHZt8GGE3khNV7Jo9