I want to start off by saying that I really like Lennon and Hollis and think they both match your current name choices really well without matching too much. I really like Hollis in particular. I think Reese is okay, but a little less exciting than the others. I also am not fond of repeating first initials (Rowan and Reese), but if that doesn’t bother you, then I don’t think it’s a big deal. I personally love Daisy as a name but dislike it for your subset, as as I don’t think it quite matches your style. My suggestions based on your current names list would probably be:
Holland (Hollis)
Ellis (Hollis)
Leighton (Lennon)
As for the rest of my suggestions, I’d like to preface by saying that I’ve actually met people with all four spellings of Devin and both spellings of Fallon, as well as two Taryns and one each of Finley, Flannery, and Maren. The ages vary, but I think each name really suited the person, so don’t be put off by any of the uniqueness! From what I’ve seen, they’re all liked and accepted by others and the women themselves.
My other suggestions:
Briony/Bryony
Bronwen/Bronwyn (Wyn as a potential nickname)
Delaney
Devan/Deven/Devin/Devon
Elowen
Fallon/Fallyn
Finley
Flannery
Jocelyn
Maren/Marin
Quinn
Tamsin
Taryn
Tatum
Teagan
My favorite is Elowen, followed by Taryn,
Quinn, and Maren:
Rowan, Cole, and Elowen
Rowan, Cole, and Taryn
Rowan, Cole, and Quinn
Rowan, Cole, and Maren
With middle names, I’d stick to the pattern of traditional names, as I think it complements your first names and offers a good balance. Some pairings I think work really well:
Elowen Abigail*
Elowen Daphne
Elowen Grace
Elowen Isobel/Isabel/Isabelle*
Elowen Rachel
Taryn Aubrey/Audrey
Taryn Amelia*
Taryn Emily
Taryn Margaret
Taryn Olivia*
Taryn Sophia
Taryn Victoria
Quinn Amelia*
Quinn Catherine/Katherine
Quinn Charlotte
Quinn Hannah
Maren Elaine
Maren Emily
Maren Margaret
Maren Olivia
Maren Sophia
My favorites are Elowen Abigail, Elowen Isabel, Taryn Amelia, Taryn Olivia and Quinn Amelia (marked by asterisks). I think each would work really well and add a similar but distinct feel to your sibling set. Elowen Abigail and Taryn Olivia are my personal favorites, but I think all would be amazing with your other children:
Rowan Elizabeth, Cole Michael, and Elowen Abigail
Rowan Elizabeth, Cole Michael, and Elowen Isabel
Rowan Elizabeth, Cole Michael, and Taryn Amelia
Rowan Elizabeth, Cole Michael, and Taryn Olivia
Rowan Elizabeth, Cole Michael, and Quinn Amelia
I’m sorry, I know this a lot of information but hopefully some of these options stand out to you and make you feel confident about choosing a name! You have a lot of great options to work with and a lovely sibsst to build off of. Best of luck!