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
['dBG AGE GED DEG GAB AGA', 'Bdd Bee d2 d dBG']  
X:1
L:1/8
M:6/8
K:G
|: d | dBG AGE | GED DEG | GAB AGA | GAB ABd | dBG AGE | GED DEG | GAB AGA | BGG G2 :: A | 
 Bdd Bee | d2 d dBG | GBd ege | dBG A2 G | Bdd Bee | d2 d dBG | GAB AGA | BGG G2 :|  