[Findegil]

I don't think that a time of relative peace is the time when Orodreth would send away his wifw and son. In all situations that Tolkien envisaged for that journey it was time of stress and realisation of the danger that the father and/or the relam was in not a time of breathtaking and temporary peace.

One possibility abot Gil-galad would be to let his mother-name be Gilgalad = Starlight and his later epesse Gil-galad = Star-of-Radiance given for his shiny armour. But that might be a bit artifical.
If we only name him Ereinion here, the read might be lost who he is. Thus if we decide to take only Gil-galad as his name I would think, we have to insert some phrase like: 'and with her went their son, [Ereinion,] yet an elvenchild, {and Gilgalad Starlight he was called for the brightness of his eye}[who later was called Gil-galad].>'

Respectfully
Findegil