Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/4
K:D
['AD FD/F/', 'BB/d/ ff g/f/e/d/ cc/d/']  
X:1
L:1/8
M:2/4
K:D
|:"A7" A/A/ |"D" AD FD/F/ | AD FD/F/ |"A7" GE CE |"D" Dd"^(A7)" c/d/c/B/ |"D" AD FD/F/ | AD FD/F/ | 
"A7" GE CE | ED"^D fine" D :: z |"G" GB GB | GB B/d/c/B/ | GB GB | GB B/d/c/B/ |"D" AD FD/F/ | 
 AD FD/F/ |"A7" GE CE | ED"D" D :: d/c/ |"Bm" BB/d/ ff | bf"^(Em)" g/f/e/d/ |"F#7" cc/d/ ee | 
 f/e/d/c/"Bm" dB | BB/d/ ff | bf"^(Em)" g/f/e/d/ |"F#7" cc/d/ f/e/d/c/ |"Bm" BB B :|  