Construct a musical piece by amalgamating the designated alphabetical representation and the supplied musical theme.
X:1
L:1/8
M:4/4
K:G
['B2{d} cB/c/ d2 g2 (f/g/a) dg (f/g/a)', 'g3 d BGBd gbag faab']  
X:1
L:1/8
M:4/4
K:G
 B2{d} cB/c/ d2 g2 | (f/g/a) dg (f/g/a) d>c | B2{d} c/B/c d2 c'2 | (3bag (3fga bg g2 :: g3 d BGBd | 
 gbag faab | c'abg afge | f2{a} gf/g/ afed | g3 d BGBd | gbag faab | aabg afge | dgfa bg g2 :|  