I’m due in a week and we’re so far from naming our second daughter. I would like it to flow with big sister [name]Miriam[/name]. We do agree on [name]Bea[/name] for middle name. I like [name]Eden[/name], [name]Ada[/name], [name]Sybil[/name]. Husband is more into androgynous names ([name]Frankie[/name], [name]Billie[/name], etc). Any suggestions???
Of the names you have, [name]Bea[/name] works best as a middle for [name]Ada[/name]. [name]Eden[/name] [name]Bea[/name] is too much long ee sound (sounds like eatin’ bee, I do like the name [name]Eden[/name] though), and [name]Sybil[/name] [name]Bea[/name] is too much B back to back for me.
I also think [name]Miriam[/name] and [name]Ada[/name] go the nicest together. [name]Both[/name] vintagy while having a pretty vibe ([name]Sybil[/name] is more serious).
Some names that go with [name]Miriam[/name] and that your style reminds me of are:
[name]Edina[/name] [name]Bea[/name] (nn [name]Eddie[/name]?)
[name]Sylvia[/name] [name]Bea[/name]
For your husband’s interests but still not wildly different style I could see…
[name]Miriam[/name] [name]Rae[/name] and [name]Willa[/name] [name]Bea[/name] (nn [name]Billie[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Frances[/name] [name]Bea[/name] (nn [name]Frankie[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Natalie[/name] [name]Bea[/name] (nn [name]Nate[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Andrea[/name] [name]Bea[/name] (nn [name]Andie[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Louisa[/name] [name]Bea[/name] (nn [name]Lou[/name], [name]Louie[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Alice[/name] [name]Bea[/name] (nn [name]Alli[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Alexandra[/name] [name]Bea[/name] (nn [name]Allie[/name], [name]Alex[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Nicola[/name] [name]Bea[/name] ([name]Nikki[/name])
[name]Miriam[/name] [name]Rae[/name] and [name]Daniela[/name] [name]Bea[/name] ([name]Dani[/name])
I love [name]Alice[/name] & [name]Alexandra[/name]. 
For [name]Alice[/name], (Or for [name]Alexandra[/name], though you have the [name]Alex[/name] option for that) if you wanted a more androgynous nn, (like [name]Lou[/name] for [name]Louise[/name]) you could go with [name]Al[/name]. I think it would be cute…
[name]Miriam[/name] and [name]Ada[/name] would be my choice. Although have you considered a longer name shortened to [name]Ada[/name]?
[name]Miriam[/name] and [name]Abigail[/name]
[name]Miriam[/name] and [name]Naomi[/name]
[name]Miriam[/name] and [name]Susannah[/name]
[name]Miriam[/name] and [name]Tabitha[/name]