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 (3def dega dBAB G2 GF']  
X:1
L:1/8
M:4/4
K:G
|: BA |"G" G2 Bc d2 (3def |"C" ga ge"G" de fg |"Em" ab ge"G" dB GA |"Am" BA AG"D7" (3ABc GA | 
"G" GABc"Bm" dB (3def |"C" gage"G" dega |"Em" bage"D" dBAB |"G" G2 GF G2 :: fg |"D" afd^c"G" dega | 
"Em" bgef efga |"G" bgaf"C" gedB |"Am" BAAG"D7" (3ABc BA |"G" GABc dB (3def |"C" gage"G" dega | 
"Em" bage"D" dBAB |"G" G2 GF G2 :|  