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
['B3 AGF', 'TB3 Tc3 BGG ABd']  
X:1
L:1/8
M:6/8
K:G
 B3 Bdc | B3 AGF | DGG AGF | AGG Adc | B3 BdB | B3 AGF | FGA/B/ cAA | FDE FGA :: TB3 Tc3 | 
 BGG ABd | g3 gdB | dgg fdc | TB3 Tc3 | BGG ABd | fef gdB | EDE FGA :|  