Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/4
M:3/4
K:D
['d2 (3e/f/g/ f', 'e3 A c c/e/ A d d/f/', 'D A, C D', 'A, A,']  
X:1
L:1/4
M:3/4
K:D
 D F A | d2 (3e/f/g/ | f d c | d2 (3e/f/g/ | f D (3f/g/a/ | g E f/g/ | a c d/f/ | e3 :: A c c/e/ | 
 A d d/f/ | A e e/g/ | f2 e | d f a | d' d/c/ d | e/g/f/e/d/c/ | d3 :| 
[M:3/4]"^Trio" !fermata!D2 A,/D/ | F2 D/F/ | A2 F/A/ | d D D | A, C D | A, C D | A ^C D | [EA,]3 :: 
 a a/g/ a | A, A, A, | A G/F/E/D/ | A, A, A, | D2 A,/D/ | F2 D/F/ | A2 F/A/ | d D D | A, B, C | 
 D3 :|  