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
['', 'GA B2 dB eBdB AGFE D2 EF', 'B2 G2']  
X:1
L:1/8
M:4/4
K:G
 GA |: B2 dB eBdB | AGFE D2 EF | GFGE DEGB | dBeB A2 GA | B2 dB eBdB | AGFE D2 EF | GFGE DEGA |1 
 B2 G2 G2 :|2 B2 G2 G3 F |: EDEF GFGE | DGBe d2 Bd | e2 ed BcBA | GABG A2 GA | B2 dg bage | 
 dBGA B2 BA | GFGE DEGA |1 B2 G2 G3 F :|2 B2 G2 G3 ||  