Imagine, if you will
It does not take Maglor and Maedhros very long to give Elrond and Elros father names.
Oh, they try to resist it of course. They truly do feel terrible about the whole kidnapping ordeal. (Maglor feels horrible about many, many things, Maedhros even worse, not that that has ever stopped their blades.)
They have already taken so much from Elwing and Eärendil. Maglor especially does not wish to take their place in traditional naming conventions. (Neither of them know if Eärendil intended to name the peredhel with Noldor customs, they can’t very well ask.)
Still, both Maglor and Maedhros have spent centuries full naming their younger brothers (“CELEGORM TYELKORMO TURCAFINWË YOU GET BACK HERE RIGHT NOW OR SO HELP ME”).
As it turns out you just can’t quite fit the right amount of all consuming wrath and disapproval into just “ELROND” or “ELROS”.
The twins have father names within the year.
Hah! I can see that!