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=180
M:6/8
K:D
['', 'B2 A B2', 'd Bcd']  
X:1
L:1/8
Q:1/8=180
M:6/8
K:D
 A |: DED E2 F | d2 c B2 A | B2 A B2 d | e3 def | DED E2 F | d2 c B2 A | B2 A B2 c | d3- d2 A :: 
 d2 f e2 d | Bcd A2 F | A2 A g2 f | f3 eag | f2 a f2 d | Bcd AGF | A2 A B2 c |1 d3- d2 A :|2 
 d3- d2 ||  