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
['BDGB cBce (3dcB gf agfg ecGc', 'G2 B,C DGBd gfag bg (3agf gdBG']  
X:1
L:1/8
M:4/4
K:G
|: dc | BDGB cBce | (3dcB gf agfg | ecGc egfg | af (3gfe dedc | BDGB cBce | (3dcB gf agfg | 
 ecGc egfe | dcAF G2 :: B,C | DGBd gfag | bg (3agf gdBG | (3EFG AB cBce | af (3gfe dedc | 
 BDGB cBce | (3dcB gf agfg | ecGc egfe | dcAF G2 :|  