Construct a musical piece by amalgamating the designated alphabetical representation and the supplied musical theme.
X:1
L:1/4
M:3/4
K:G
['B3/2 A/ B G2']  
X:1
L:1/4
M:3/4
K:G
 B3/2 A/ B | G2 A | (G F) E | D3 | B3/2 A/ B | G2 E | (F A2-) | A2 z | B3/2 A/ B | G2 G | (G F) E | 
 D2 D/D/ | D G G/G/ | (F G) A | G3- | G2 z |]  