[name_u]Marian[/name_u] and [name_f]Miriam[/name_f] are too close. [name_u]Vivian[/name_u] could work with either of them though.
I would stay away from rhyming ā-iahā siblings.
[name_u]Marion[/name_u] strikes me as old, on either gender. [name_m]Arthur[/name_m] could be a sibling, or [name_f]Dorothy[/name_f], [name_f]Hester[/name_f], [name_m]Seymour[/name_m], [name_m]Harold[/name_m], [name_m]Leonard[/name_m].
[name_f]Miriam[/name_f] and [name_m]Abraham[/name_m] both make me think OT names: [name_m]Gideon[/name_m], [name_m]Josiah[/name_m], [name_f]Esther[/name_f], [name_f]Delilah[/name_f]. Sisters of the two Miriams I know IRL are [name_f]Lillian[/name_f] and [name_f]Joanna[/name_f].
[name_u]Vivian[/name_u] goes with so many old-but-new-again names that are popular right now: [name_f]Beatrice[/name_f], [name_f]Matilda[/name_f], [name_f]Rosalie[/name_f], [name_f]Margot[/name_f], [name_u]Evelyn[/name_u], [name_f]Hazel[/name_f], [name_u]August[/name_u], [name_m]Frederick[/name_m], [name_m]Edwin[/name_m], [name_u]Oliver[/name_u].
[name_m]Arthur[/name_m] can also in Vivianās sibset, though I think of it as a bit mustier, fitting in with stodgy British royal names like [name_u]George[/name_u] and [name_m]Alfred[/name_m] or uppity picks like [name_m]Rupert[/name_m] or [name_u]Remington[/name_u].
[name_m]Jeremiah[/name_m] sounds country to me, honestly. I could see his siblings as [name_m]Judson[/name_m], [name_u]Cassidy[/name_u], and [name_f]Willodean[/name_f].
[name_f]Moriah[/name_f] goes with more obscure Biblical names: [name_f]Keturah[/name_f], [name_m]Mordechai[/name_m], [name_m]Jotham[/name_m], [name_m]Abdiel[/name_m].
[name_u]Lawrence[/name_u] is more midcentury to me, so itās still awaiting its comeback. His siblings could be [name_u]Robert[/name_u], [name_m]Richard[/name_m], [name_m]Franklin[/name_m], [name_u]Evelyn[/name_u], [name_u]June[/name_u], [name_f]Edith[/name_f], [name_u]Louise[/name_u].