Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/4
M:2/2
K:Gmix
['c c', 'B/c/ d e/d/ c2', 'A B']  
X:1
L:1/4
M:2/2
K:Gmix
 G/^F/G/A/ B/G/A/B/ | c c c2 | B/A/B/c/ d c/B/ | A A A2 | G/^F/G/A/ B/G/A/B/ | c c c B | A B A2 | 
 G2 G2 :: B/c/ | d e/d/ c2 | B3 B/c/ | d e/d/ c2 | B4 ::[M:3/4] B A B | G A B | c2 c | c2 B | 
 B c d | d c B | A2 A | A2 B | B A B | G A B | c2 c | c2 B | A2 B | A3 | G3 :|  