Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/16
M:2/4
K:G
['gdBd GBdg edef agfe dgfe', 'bagb agfa gfeg fedf edce']  
X:1
L:1/16
M:2/4
K:G
 (3def | gdBd GBdg | edef agfe | dgfe dBGB | edcB A2(3def | gdBd GBdg | edef agfe | dgfe dcBA | 
 G2b2G2 :: (ga) | bagb agfa | gfeg fedf | edce dBGB | edcB A2(ga) | bagb agfa | gfeg fedf | 
 edce dfga | bagf g2 :|  