We aren’t set on another M name and that seems to make it harder. We do not know gender.
[name_u]Morgan[/name_u]
[name_u]Mischa[/name_u]
[name_f]Mila[/name_f]
[name_m]Roman[/name_m]
[name_u]Noah[/name_u]
[name_u]Sacha[/name_u]
[name_f]Sophie[/name_f]
[name_f]Noa[/name_f]
[name_f]Larissa[/name_f]
WDYT?
[name_m]Miles[/name_m]
[name_u]Marshell[/name_u]
[name_m]Mitchell[/name_m]
[name_m]Milo[/name_m]
[name_m]Miller[/name_m]
[name_m]Liam[/name_m]
[name_m]Samuel[/name_m]
[name_m]Alan[/name_m]
[name_m]Andrew[/name_m]
[name_m]Thomas[/name_m]
[name_f]Maria[/name_f]
[name_f]Matilda[/name_f]
[name_f]Mckenzie[/name_f]
[name_f]Molly[/name_f]
[name_u]Morgan[/name_u]
[name_f]Melany[/name_f]
[name_f]Clara[/name_f]
[name_f]Ann[/name_f]
[name_f]Beatrice[/name_f]
[name_f]Charlotte[/name_f]
I have a weird preference for either all sibling names starting with the same letter, or no sibling names starting with the same letter. It’s kind of an all-or-nothing thing for me. So, I would go with an M. Plus if it’s making it harder to NOT come up with an M name, then go with an M name if it seems more natural to you 
[name_f]Marigold[/name_f]
[name_f]McKenna[/name_f]
[name_f]Maeve[/name_f]
[name_f]Mia[/name_f]
[name_f]Melody[/name_f]
[name_f]Mirabelle[/name_f]
[name_f]Mina[/name_f]
[name_f]Minette[/name_f]
[name_m]Magnus[/name_m]
[name_m]Malachi[/name_m]
[name_m]McKinley[/name_m]
[name_m]Marshall[/name_m]
[name_m]Marvin[/name_m]
[name_m]Mateo[/name_m]
[name_m]Miles[/name_m]