Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
Q:1/2=90
M:2/2
K:D
['DAFA DAFA defe dcBA eAfB', 'Addd cdec']  
X:1
L:1/8
Q:1/2=90
M:2/2
K:D
 (FE) | DAFA DAFA | defe dcBA | eAfB gBfB | edcB AGFE | DAFA DAFA | defe dcBA | eAfB gBec | 
 d2 g2 d2 :: f2 | eAAA fBBB | gBBB aBBB | eAfB gBfB | edcB AGFE | Addd cdec | Addd cdec | 
 dfed cABc |"^NB" d2 g2 d2 |]  