Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:6/8
K:D
['BAG FGE DFA AFA dfd', 'f3 gfg afd']  
X:1
L:1/8
M:6/8
K:D
 fAA fAA | BAG FGE | DFA AFA | dfd e2 d | fAA AFA | BAG FGE | DFA AFA | dfd e2 d :: f3 gfg | 
 afd fed | f3 gfg | afd e2 d | f3 gfg | afd edB | A2 A AFA | dfd e2 d :|  