Construct a musical piece by amalgamating the designated alphabetical representation and the supplied musical theme.
X:1
L:1/4
M:4/4
K:C
['B A', 'B A']  
X:1
L:1/4
M:4/4
K:C
[K:G] .B3/2 c/ B A | B d D c | B3/2 c/ B A | B d D c | B A c B | A d G B/G/ | E A D F | G G z2 | 
 B2 G2 | d2 B B | g3 d | d2 z c | B A c B | A d G B/G/ | E A D F | G G z2 || B3/2 c/ B A | 
 G B d D | E A F D | D G z2 | B3/2 c/ B A | G B d B | A G F E | D D z2 | c3/2 B/ A G | A d D c | 
 B3/2 A/ G A | B d D c | B A c B | A d G B/G/ | E A D F | G G z2 ||  