Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/16
M:2/4
K:G
['B2dB G2G2', 'g2fe dBG2 e2dc B4 GAB2 cde2 d2F2']  
X:1
L:1/16
M:2/4
K:G
|: B2dB G2G2 | A2GA B2G2 | B2dB G2G2 | A2BA G2 z2 | B2dB G2G2 | A2GA B2G2 | B2dB G2G2 | A2BA G4 :: 
 g2fe dBG2 | e2dc B4 | GAB2 cde2 | d2F2 G2 Bd | g2fe dBG2 | e2dc B4 | GAB2 cde2 | d2F2 G4 :|  