I love both
Miriam and
Jonas -- great choices.
My favorite mn with
Miriam is
Susanna, pronounced "soo-SAH-na." Perhaps it could work as a sibling too.
Other suggestions for siblings to
Miriam and
Jonas:
Sylvia,
Eve /
Eva,
Rose,
Sibyl,
Renata,
Fredrika,
Simone,
Gabrielle,
Petra,
Greta,
Lena,
Rebecca,
Cornelia (
Nell),
Peter,
Benedict,
Henry,
Kurt,
Fredrik,
Stephen /
Stefan,
Erik,
Isaac,
Max,
August,
Anton,
Oscar /
Oskar.
Miriam and
Jonas seem to make me channel Scandinavian names. Weird.