Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/8
M:4/4
K:C
['aed cBA', 'B A2 a aec']  
X:1
L:1/8
M:4/4
K:C
 BEA |[M:6/8][K:A]SOSOO .!fermata!PMTuCOMf | aed cBA | ecA A2 g | aed cBA | dBG G2 g | aed cBA | 
 def efg | agf =gfe | dBG A2 :: B | A2 a aec | aec ABA | =G2 g gdB | =gdB G2 B | A2 a aec | 
 def efg | agf =gfe | dBG A2 :|  