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
['dddcBA GGGBAG FFFcBA', 'D2 E2 G2 (FE) D2 B2 (AG)']  
X:1
L:1/8
M:3/4
K:G
 (GB) | dddcBA | GGGBAG | FFFcBA | GGGDGB | dddcBA | GGGBAG | FFFcBA | G2 z2 :: D2 | E2 G2 (FE) | 
 D2 B2 (AG) | F2 c2 (BA) | G2 B2 D2 | E2 G2 (FE) | D2 B2 (AG) | F2 c2 (BA) | G2 z2 :|  