Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
Q:1/4=120
M:6/8
K:D
['D DFA dcd BAG FGE DFA dBe', 'AFD E2 D']  
X:1
L:1/8
Q:1/4=120
M:6/8
K:D
 D | DFA dcd | BAG FGE | DFA dBe | cAA A2 =c | BGB Bcd | AFD E2 D | DEF GEA | FDD D2 :: A | 
 FAF GBG | AFD E2 D | FGA Bcd | cAA A2 =c | BGB Bcd | AFD E2 D | DEF GEA | FDD D2 :|  