Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/8=180
M:6/8
K:C
['GBd cAF', 'G2 A Fff fed cdc cAF Ggg']  
X:1
L:1/8
Q:1/8=180
M:6/8
K:C
|: c | B3 GBd | cAF F2 c | BAB GBd | cBc edc | BdB GBd | cAF ABc | BdB cAF | AGG G2 :: A | 
 Fff fed | cdc cAF | Ggg g^fg | afd d2 e | fgf fed | cAF FAc | B/c/dB cAF | AGG G2 :|  