Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:G
['DED DEG A2 G ABc BAG AGE', 'dBG AGA', 'A2 D']  
X:1
L:1/8
M:6/8
K:G
|: DED DEG | A2 G ABc | BAG AGE | GEA GED | DED DEG | A2 G ABc | BAG AGE | GED D3 :: ded dBG | 
 AGA BGE | ded dBG | AGA G3 | g2 e dBG | AGA BGE | B2 G AGE | GAG G3 :: A2 D B2 D | A2 D ABc | 
 BAG AGE | GEA GED | A2 D B2 D | A2 D ABc | BAG AGE | GED D3 :|  