Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:C
['G2 G/G/ AGG']  
X:1
L:1/8
M:6/8
K:C
 E | G2 G/G/ AGG | c2 c/c/ AGE | G2 G/G/ AGG | cde d2 G | G2 G/G/ AGG | c2 c/c/ AGE | GGG AGG | 
 cde c2 ||  