How are their backgrounds too different? Both names are used in the Netherlands and other European countries in a close proximity. It's not like I am putting Ga-In and
Luisa in a sibset. I just don't see the problem there and have no idea what you mean by saying that they wouldn't be "believable" as a sibset
“She’s mad, but she’s magic. There’s no lie in her fire.” -
Charles Bukowski
http://www.behindthename.com/pnl/147561http://www.babynames.com/namelist/9852886