Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:G
['DGG GFG ABc d2 e', 'gfg def gfg a2 g']  
X:1
L:1/8
M:6/8
K:G
|: F | DGG GFG | ABc d2 e | fef ded | cAG FEF | DGG GFG | ABc d2 e | fed cAF | G3 G2 :| d | 
 gfg def | gfg a2 g | fef ded | cAG FGA | gfg def | gfg a2 g | fed cAF | G3 G2 d | gfg def | 
 gfg a2 g | fef ded | cAG FGA | B3 BAG | ABc d2 e | fed cAF | G3 G2 ||  