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
['G2Bd g2fe (FG)AB (3(cdc)(BA)', 'd2B2 (dg)fg e2c2 (ea)^ga f2d2 d2ef']  
X:1
L:1/16
M:2/4
K:G
 G2Bd g2fe | !plus!d2!plus!G2 !plus!B2!plus!G2 | (FG)AB (3(cdc)(BA) | G2e2 (dc)BA | G2Bd g2fe | 
 !plus!d2!plus!G2 !plus!B2!plus!G2 | (FG)AB (3(cdc)(BA) | A2G2 G4 :: d2B2 (dg)fg | e2c2 (ea)^ga | 
 f2d2 d2ef | g2b2 (ba)ge | d2B2 (dg)fg | e2c2 (ea)^ga | f2d2 d2ef | g2g2 g4 :|  