Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:G
['dB gB dB', 'g>a ge']  
X:1
L:1/8
M:4/4
K:G
 B | G/A/B/c/ dB gB dB | gB dB aA AB | G/A/B/c/ dB gB dB | cA dc BG G :: f | g>a ge a>b af | 
 g>a ge be ef | g>a ge a>b af | gd e>c BG G :|  