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:G
['A2 d2 B2']  
X:1
L:1/8
M:4/4
K:G
!mf! vG2 B2 | A2 d2 B2 AG | A2 d2 B2 eG | F2 dF E2 ^c2 | d4!p! G2 B2 | A2 d2 B2 AG | A2 d2 B2 eG | 
 F2 dF E2 ^c2 | d4!mf! vd2 gd | e2 d2!p! (Bd) gd | e2 d2!f! Bd gf | fe ed dc Bd | A4 ud2 G2 | 
 AF G z dB AG | AF G z ud2 GA | Fc BA B2 AG | G4 |]  