Construct a musical piece by amalgamating the designated alphabetical representation and the supplied musical theme.
X:1
L:1/8
M:3/4
K:D
['d2 (e/f/)', 'd2 f2 gfed bagf gag f2 e2']  
X:1
L:1/8
M:3/4
K:D
 d2 (e/f/) | d2 (e/f/) | (df)ga | (fg)(ec) A2 | (A/B/c/e/) (ABce) (A/B/c/) | fgec d2 :: f2 | gfed | 
 bagf | gag f2 | e2 d2 | efed | c2 d | ec | d2 c2 | de d3 :|  