Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:3/8=110
M:6/8
K:G
['G2 G', 'agf gfe']  
X:1
L:1/8
Q:3/8=110
M:6/8
K:G
 G2 G GBd | ecB A2 B | G2 G dBG | edf E2 :: e/f/ | gfd agf | gfe def | gfe agf | gfg e2 g | 
 gfe agf | gfe efg | G2 G dBG |"^1" ede E2 |]  