as i know the prince title goes only with the line of the oldest son.the title stays with the Romodanovskiy-Ladyzhenskiy line.this line,as far as i know,died off.the ladischensky line is not directly related to this line.segei was the one who came to copenhagen in 1917.his son feodor was born in 1917 in copenhagen.tanja ladischensky, she named herself princesse, was the daughter of sergei.next generation is alexis,peter,natasha ladischensky.i have some information about the family prior to the revolution.