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
['G2 B', 'd3 dcB def gdB']  
X:1
L:1/8
M:6/8
K:G
 G(BA) G2 B | def geB | A(BA) G2 B | ABA AFD | G(BA) G2 B | def gdB | ecA dBG | FDF G3 :: d3 dcB | 
 def gdB | d3 dcA | ABA AFD | d3 dcB | def gdB | ecA dBG | FDF G3 :|  