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:2/2
K:G
['AGEG DGGB', 'g2 ge']  
X:1
L:1/8
Q:1/8=180
M:2/2
K:G
 GE | DGGB AGGB | dGBG AGEG | DGGB AGGg | dgdB AGEG | DGGB AGGB | dGBG AGEG | DGGB AGGg | 
 dgdB G2 || ef | g2 ge dgge | dBGB AG E2 | g2 ge degb | agab a2 ga | bagb ageg | dGBG AGEG | 
 DGGB AGGg | egdB G4 |]  