Brother or sister for Elea

Samara or Imara

What a beautiful name.
I think it's hard to find anything better for that.

For a girl:
Aira, Aria, Arisa, Avia, Ayla, Cato, Cilou, Faja, Febe, Ilja, Inez, Imke, Isha, Isra, Jara, Junia, Lexi, Liora, Liva, Loïs, Loua, Nika, Niké, Nila, Novi, Orla, Riva, Tara, Ziva, Zyra

For a boy:
Abel, Alec, Aron, Axel, Boaz, Bodi, Ezra, Finn, Ilan, Ilay, Imre, Ivar, Jack, Jaïr, Jari, Joas, Joël, Kaja, Lenn, Levi, Liam, Mels, Moos, Nilo, Odin, Olav, Otis, Quin, Ravi, Revi, Roan, Senn, Tias, Vigo, Zion

Indeed, a very beautiful name, wow, Elea Dani Roosmarijn!
I immediately think of the name Isaï (as far as I know, a unisex name, but originally a boy's name). Elea and Isaï, I find sound very beautiful together. So I think that's a nice option for you. Below are also some other ideas:
M:
Isaï Alix Loïse Louve Lorèn Desi Elize Felice Myra Maja Maire Maite Fauve Kae Sera Sari Vere Nieve Jula Mara Lova Neva Phaedra Vedra Veda Flora Céla Nola Meja Ylva Fenja Kyra Reza Rhea Rhodé Madée Riva Reva Carmen Amée Aimée Kess Vieve/Vive Dali Juna/Yuna Juno Jonna Loué Suse Niké
Favorites:
Elea and Alix
Elea and Loïse
Elea and Rhodé
Elea and Amée
J:
Isaï Rune Nils Joas Silas Bodi/Bodhi Mika Ferre Maël Naël Natan Nolan Milas Fabe Felix Jaël Jaïr Manoa(h) Jaron Sion/Zion Levi Cesar Ravi Remi/Remy Monte Benja Jules Emil Miel Mels Raúl Beau Quin Leo Theo
Favorites:
Elea and Isaï
Elea and Maël
Elea and Fabe
Elea and Remi/Remy
Elea and Théo