Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
Q:1/8=160
M:6/8
K:G
['B dBG', 'deg aga bge', 'B2 G A2 G']  
X:1
L:1/8
Q:1/8=160
M:6/8
K:G
 B | dBG BAG | dBG G2 B | dBG AGE | GED D2 B | dBG BAG | dBd BAG | AGA BAB | GED D2 :| B | 
 deg aga | bge edB | deg aga | bge ega | bag age | ged ege | dBG AGE | GED D2 :| d/c/ | B2 G A2 G | 
 B2 D Ddc | BAG AGE | GED Ddc | B2 G A2 G | BdB BAG | AGA BAB | GED D2 :|  