Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:3/4
K:G
['G2 gf g2', 'cA B2 BA BG']  
X:1
L:1/8
M:3/4
K:G
|: G2 gf g2 | G2 gf g2 | ag fe dc | Bc dB G2 | G2 gf g2 | G2 gf g2 | fa fd e^c |1 d2 dc BA :|2 
 d4 |: B2 | c2 cB cA | B2 BA BG | A2 AF AF | G2 E2 B2 | c2 cB cA | B2 BA BG | DE FG AB |1 G4 :|2 
 G6 ||  