Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:3/8=120
M:6/8
K:G
['G2 G GFG A2 A ABc', 'G2 z ddd ddd dgb d3 ccc']  
X:1
L:1/8
Q:3/8=120
M:6/8
K:G
 D | G2 G GFG | A2 A ABc | B2 B Bcd | edc BcA | G2 G GFG | A2 A ABc | B>cB AGF | G2 G G2 :: z | 
 ddd ddd | dgb d3 | ccc ccc | cea c3 | B2 B Bcd | A2 A ABc | BAG dcB |!D.C.! B3 A2 :|  