The Krohn is an add-on should we not have enough vintages. There is no obvious connection with Kopke - apart from they begin with "K". If there are enough vintages of Kopke Vintage Port (or St Luiz Single Quinta) out there amongst the Port forum I will drop the Krohn to a later date.
Let me know if you can attend and what you have.
Below all available
1. Joao (Sogevinous (Kopke))
2. Carlos (Winemaker Sogevinous)