Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/8
M:3/4
K:G
['FG A2']  
X:1
L:1/8
M:3/4
K:G
 D2 G4 | FG A2 G2 | G2 B4 | AB c2 B2 | d4 e2 | dBcBAG | FA d4 | FG A2 G2 |]  