–It's a Girl!
It sounds as if you and your husband might be closer to agreement than you think. Set aside, for a moment, the idea of modern vs. old-fashioned names, and listen to the sounds of the names you mentioned. Now they have a lot more in common: the vowel sounds "ee" and "ah," and the consonants L and M.
–My Three Sons
The idea of sibling name "flow" is a new one for me. Name flow typically applies to a single name's different components—to the smooth sound pattern of first-middle-last name combinations rather than to an easy verbal transition between three sibling names. But whether you're worried about the three brothers' names falling trippingly on your tongue or have the more common concern of wanting your kids' names to "go together"—to sound like a matched set—you've got the same major issue at stake: To –er or not to –er?
–Like Mother, Like Daughter
It seems to me that your baby would already have her own name: Elliana. But let's look at the question of what constitutes an homage: What's the best way to honor your mom in her granddaughter's name? Generally, the standard is: Will the honoree (or if she is deceased, the people who loved and remember her) feel suitably honored by the name you choose?
We should distinguish here between honor names and name associations. An honor name, of course, is one you give to your child as a way to show admiration, respect, and love for the honoree. It's a deliberate choice to have your child share his name with someone who is important to you.
The real question here might be "What is an 'Irish version' of a name?" That’s because American or English names are linked to Irish names in varying (and inconsistent) ways. For example, the Irish name Aoife is often called the Irish version of Eve or Eva—but only because the two names sound similar. They don't share an etymology. But the Irish name Séamus and its English counterpart, James, actually derive from the same source and refer to the same Biblical name.
Sometimes, a change like this just takes a lot of gentle, but persistent reminders, as when a teenager or adult wants to shed a childhood nickname. It’s not rude to say "It's Kellin now, thanks!" when friends forget. Just keep your tone cheerful and polite.
The meanings are not a big deal. Most people don't think of Mark as meaning "warlike" for several reasons: It's too common and classic a name for anyone to recall its etymology. The meaning isn't immediately obvious, as it would be in a word name; it comes via the Roman war god, Mars. Above all, the notion that Mark truly means "warlike" isn't terribly accurate. Yes, Mark comes from the Roman name Marcus. No one really knows the origin of that name, but scholars assume it indicated a connection or dedication to Mars.
Silence can mean many things: disinterest, polite disapproval, quiet appreciation. You interpret the silence over your daughter's name as a rejection of it by the people you speak with, and you may be right. I am not a participant in those conversations and can't read the body language and facial cues of your partners, all of which would help determine their exact stance toward "Andie" (the name, not your little girl).
Junior and a Half? That’s a new one for this Name Lady. There's really no such thing as a half-junior. It's like a half-rhyme, or being a little pregnant. Either you are, or you aren't. And while it sounds like a clever option, ISS is just not a thing. It’s true that "SS" can be used to stand for ½ in Roman numerals; pharmacists do it. But no one else does.
You haven't said just what it is about Carol that's turning you off, aside from the way it sounds with Ruby. Perhaps it's the rhythm: Your ear craves another syllable after "Carol," but you've already said you don't care for Caroline or Carolyn.
Or maybe the pairing of two word names is causing your discomfort. In either of those cases, a second middle name, either before or after Carol, could help. How about a trio like Ruby Elizabeth Carol or Ruby Carol Jane?