Develop a musical composition using the outlined alphabetical depiction of the structure and the provided theme.
X:1
L:1/4
M:6/4
K:G
['d B G', 'F c2 c d3/2 e/f/g/ e3- e2', 'c e2 d g2 e a g3/2']  
X:1
L:1/4
M:6/4
K:G
|: c2 d e c A | G3/2 A/B/c/ d B G | e2 f g e c | d B G c G F :: c2 c d3/2 e/f/g/ | e3- e2 c | 
 d2 d e3/2 f/g/a/ |1 ^f6 :|2 ^f3- f2 d |: e d2 B2 G | g f2 e2 c | e2 d g2 e | 
 a g3/2 f/ e3/2 d/ c :|  