Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/2=100
M:2/2
K:D
['A2 d4 c>dec d2 d>d d2 e2', 'f2 e2']  
X:1
L:1/8
Q:1/2=100
M:2/2
K:D
 A2 | d4 c>dec | d2 d>d d2 e2 | f4 e>fge | f2 f>f f2 e2 | dcde f2 ed | cBce a2 e2 | fafd c2 B2 | 
 A2 A>A A2 :: A2 | a4 f>dfa | g>abg e2 f2 | g4 e>ceg | f>gaf d2 A2 | d>fe>g f2 e2 | f>ag>b a2 g2 | 
 (3fga (3bag f2 e2 | d2 d>d d2 :|  