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
['gfed (BG) G/G/G', 'd2 eaaf gaba gedB']  
X:1
L:1/8
M:4/4
K:G
 (ef) | gfed (BG) G/G/G | BGdG (BG) G2 | gfed (BG) G/G/G | BGdB A2 :| fg | a2 af g2 fg | 
 a2 af ge d2 | eaaf gaba | gedB A2 (fg) | a2 (af) gabg | abaf (ge) d2 | eaaf gaba | gedB A2 ||  