[name]Eileen[/name] - [name]Eileen[/name] is an Irish variation of [name]Helen[/name], so you’ve kind of already honoured your [name]Eileen[/name] with [name]Elena[/name]! Other variations you could think about are [name]Helena[/name], [name]Nell[/name], or just plain [name]Helen[/name], which is quite pretty on its own.
[name]Elizabeth[/name] (who goes by [name]Lilly[/name]) - For [name]Elizabeth[/name], the possibilities are virtually endless. The names [name]Susan[/name], [name]Susannah[/name] and such actually mean [name]Lily[/name], so that’s a definite option. You’ve also got virtually infinite variations of [name]Elizabeth[/name] - my favourites of which are [name]Eliska[/name] (ell-ISH-kah or eh-LISS-kah), [name]Elisheva[/name], [name]Elspeth[/name] and [name]Eliza[/name]. You could also go with [name]Isabelle[/name], [name]Isobel[/name], [name]Isabel[/name], [name]Isabella[/name], [name]Bella[/name], [name]Belle[/name] and such, which are actually variations of [name]Elizabeth[/name].
[name]Kay[/name] - [name]Acacia[/name] is definitely my favourite to honour [name]Kay[/name], though [name]Kate[/name], [name]Katie[/name], [name]Kat[/name], [name]Kathy[/name]/[name]Kathie[/name], [name]Katherine[/name], [name]Kaylin[/name], [name]Kaytlin[/name] and other such variations would work too.
[name]Amy[/name] - [name]Amity[/name] was my first thought. [name]Amelia[/name] and [name]Amabel[/name] are also some good options. [name]One[/name] of your favourites, Amélie, is very usable as well to honour [name]Amy[/name].
[name]Marie[/name] - You could go with the ever-classic [name]Mary[/name], which is actually my favourite option, or variation [name]Maria[/name]. [name]Marie[/name] is also a common and quite pretty ending for hyphenated names, like [name]Anne[/name]-[name]Marie[/name]/[name]Annemarie[/name] or [name]Sophia[/name]-[name]Marie[/name], (my favourites). [name]Maisy[/name], [name]Mamie[/name], [name]May[/name]/[name]Mae[/name] and [name]Molly[/name] are also some nice variations of [name]Mary[/name] that you could use.
(Also felt I had to add that you could - for want of a better phrase - kill two birds with one stone with [name]Amelia[/name], who could go by [name]Mia[/name], honouring both [name]Marie[/name] and [name]Amy[/name] in a way.)
Good luck! 