I think it’s fine! I’m in a sibset with an [name_u]Avery[/name_u], and the others are [name_f]Keira[/name_f], [name_u]Neely[/name_u] (g), [name_m]Peter[/name_m] and [name_f]Sadie[/name_f]. [name_u]Maria[/name_u] and [name_u]Avery[/name_u] are lovely.
Here are some names to consider to pair with [name_u]Avery[/name_u]
Mairin
[name_f]Maelie[/name_f]
[name_f]Marlyn[/name_f] / [name_u]Marlin[/name_u]
[name_u]Malin[/name_u]
[name_u]Mallory[/name_u]
[name_f]Megaera[/name_f]
[name_u]Morgan[/name_u] / [name_f]Morgana[/name_f]
[name_f]Margot[/name_f] / [name_f]Margaux[/name_f]
[name_f]Megan[/name_f] / [name_f]Meghan[/name_f]
You might even consider [name_u]Marie[/name_u] or [name_u]Maria[/name_u] as a middle name with any of these names. The alliteration would make the name flow well and be very memorable.
Good luck with your decision.
Honestly, I don’t think they match, but they aren’t nearly as bad as some other sibsets I’ve seen! I like @may.rose’s idea of [name_f]Mara[/name_f] instead of [name_u]Maria[/name_u]!