i don’t think it could work, sorry! if it was a boy lowen and a girl eliza it would work, but with a name as traditionally feminine as eliza, lowen would always be presumed to be a brother. i agree with the previous poster that eliza and elowen are too close, but i love the suggestion of lowenna!
maybe you’ll like eliza & lena, lainey, lenore, laurel, lucienne, leonie, leona, liadan, linnea or lorelei?