Happy Tolkien Day!
"Elrond and Elros, children of Eärendil (sea-lover) and Elwing (Elf-foam), were so called, because they were carried off by the sons of Fëanor, in the last act of the feud between the high elven houses of the Noldorin princes concerning the Silmarils; the Silmaril rescued from Morgoth by Beren and Lúthien, and given to King Thingol, Lúthien's father, had descended to Elwing, daughter of Dior son of Lúthien. The infants were not slain, but left like 'babes in the wood', in a cave with a fall of water over the entrance. There they were found: Elrond within the cave and Elros dabbling in the water."
Letter 211, The Letters of JRR Tolkien
I was rereading Silmarillion and the "Ruin of Doriath" mentioned the early childhood of Elrond and Elros only briefly . We do need more works to flesh out what happened to the twins- Maglor raised them but not much was said in Silmarillion. More about Elros in here:
Just a moment...
tolkiengateway.net