I wasn't sure if you meant the middle names should begin and end with the same letter (like Anna) or have the same first and last letter as each other (like Nicole and Nate) so I'm going to give options for both.
Hudson Silas and Blakelee Hannah (or Hudson Raye and Blakelee Rose)
Cayden Desmond and Ashlyn Anastasia (or Cayden James and Ashlyn Jess)
River Cedric and Madison Laurel (or River Alexander and Madison Amber)
Isaac Malcolm and Kinley Willow (or Isaac Nate and Kinley Nicole)
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Around the same time as Azrael and Ashley have found out about their baby, Princess Calantha Elizabeth Serene Lark "Rellin" Atherton (40) and her husband Josiah Edmund Carter Atherton (40) discovered they are expecting their sixth and seventh children, boy/girl twins.They would like their first names to be music-related and for them to have three middle names- one should be Biblical, one should start with a vowel, and the other should start with the same letter as the baby's first name - these can be in any order. They would like 3 options per baby.
[I have bolded the expectant family, so you can see the other kids names to avoid repeats]
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Emarintha Anastasia Maria Elizabeth Rellin (59) and Alaric Edward James Redwood (62) with Kestra Rosamund Lily Faith (43), Azrael Christopher Birch (41), Calantha Elizabeth Serene Lark and Cadmus Edward Sparrow (40), Persephone Katherine Destiny Skye (36), Finvarra Jonathan Bravery (34), and Liliana Elizabeth Mesa Clarity (32)
Kestra Rosamund Lily Faith Rellin (43) and Oberon Alexandrius Arthur James Ravenlake (45) with Selena Posey Miranda and Osiris River Shane (26), Calliope Zinnia Margaret (24), Odin River Caleb (15), Persephone Clover Marie (12), Astraea Petal Marianne and Thalia Meadow Meredith (6) and Griffin Cedar Alexander (4)
Azrael Christopher Birch Rellin (41) and Ashley Marie "Curtis" Rellin (40) with Nerissa Caroline (22), Fay Emma and Elvin Noah (12), Arion James (5), and Nimueh Gabrielle (newborn)
Calantha Elizabeth Serene Lark "Rellin" Atherton (40) and Josiah Edmund Carter Atherton (40) with Harmony Esther Isobel Hannah, Sonata Bethany Shiloh Alyssa, and Lark Ezekiel Lucas Alexander (19) Reed Gideon Robert Elijah (12), and Lyric Susanna Amanda Leigh (5)
Cadmus Edward Sparrow Rellin (39) and Aviana Jasmine "Ellis" Rellin (38) with Alaric Ezekiel Blaine (19), Callista Jessamine Ivy (8), and Anastasia Clove Persephone, Aurelius Oak Demetrius, and Larkspur Reeve Amadeus (1)
Persephone Katherine Destiny Skye "Rellin" Song (36) and Elyan James Azariah Song (39) with Garreth Hawk Noble and Guinevere Aspen Joy (17) and Gawain Forest Valor (8)
Finvarra Jonathan Bravery Rellin (34) and Ariana Lyric Sophia "Caden" Rellin (32) with Bethan Avery Aurora (13), Tanwen Jamie Seraphina, Sawyl Caden Patrick, Eleri Caspia Mirabelle and Macsen Emar Philip (11), and Seren Victoria Lily (2)
Liliana Elizabeth Mesa Clarity "Rellin" Jamison (32) and Uriah Alexander Cade Jamison (34) with Rosalie Alexandra Kitty (15), Oakland Maxwell Jack (8), and Gwydion Theodore Jeb (1)
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Last Family (complete):
Jenna May "Brown" Rosewood (62) and Allen Jay Rosewood (62) with Kenna Hailey (44), Lana Bailey (44), Naveen Kailey (44), Justice Levi (41), Trinity Esther (41), and Hermione Claire (39).
Lana Bailey "Rosewood" Sparks (44) and Alexander Nicholas Sparks (44) with Hallie Ava (28), Kaiden Menelaus (23), Lena Ashley (16), and Maddox Mordecai (10)
Kenna Hailey "Rosewood" Tyler (44) and Xerxes Axel Tyler (45) with Pepper Artemis and Falcon Apollo (23) Whimsy Athena (21), and Midnight Ajax, Moon Asteria, and Evening Hera (6)
Naveen Kailey "Rosewood" Black (44) and Jacob Oliver Black (44) with Narelle Sophia (22), Liam Isidore (19), and Amoret Ava and Bethan Mia (15)
Justice Levi Rosewood (41) and Ella Jane "Smith" Rosewood (37) with Grace Helena and Hope Annemarie (18), Merit Alexander (14), and Valor Benjamin (4)
Trinity Esther "Rosewood" Di'Angelo (41) and Adriano Carmine Di'Angelo (43) with Levi Eduardo (17), Lorelai Bianca (15), Lark Isabella (12), and Lydia Rose and Laban Romeo (2)
Hermione Claire "Rosewood" Snow (39) and Jonah Daniel Snow (37) with Athena Abigail (16), Noah Perseus (13), Micah Icarus and Iris Miriam (9), and Calypso Martha and Echo Hadassah (newborn)