63.29Level 10 — Dorian versus Aeolian triad pair

For C Aeolian:

D diminished-ish structures may become more awkward because A becomes A♭.

Instead try:

E♭ major + F minor.

E♭: E♭ G B♭.

Fm: F A♭ C.

Combined:

C E♭ F G A♭ B♭.

Missing D.

Strong natural-minor collection.