Develop a musical composition by integrating the alphabetically represented musical pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:G
['G GAG']  
X:1
L:1/8
M:6/8
K:G
"G" d2 B BcB |"D" def"C" gfe |"G" d2 B"Em" BcB |"Am" A2 B"D7" cBA |"G" d2 B BcB |"D" def"C" gfe | 
"G" dBG"D7" DEF |"G" G3 G3 |]:"G" D2 G GAG |"G" B2 G GAG |"Am" E2 A ABA |"D7" cBA GFE | 
"G" D2 G GAG |"G" B2 G GAG |"G" dBG"D7" DEF |"G" G3 G3 :|  