Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/4
M:3/4
K:G
['G F', 'd B/c/ d']  
X:1
L:1/4
M:3/4
K:G
 D | G2 D | G A B | c2 B | A2 G | G F E | D E D | F2 G | A2 c | B A G | B c d | e2 A | A2 G | 
 G F E | D G F | G3 | G2 |] B | d B/c/ d | d B/c/ d | G B G | G B G | e c/d/ e | e c/d/ e | A c A | 
 A c A | B c d | e f g | f g a | d2 c | B2 G | A B A | G3 | G2 |]  