Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:C
['F>(D (3EFG) A2 (AB) c2 (cd) cAGB', 'fdeg fdec']  
X:1
L:1/8
M:4/4
K:C
 BEA |[M:2/2][K:D]SOSOO .!fermata!PMTuCOMG | F>(D (3EFG) A2 (AB) | c2 (cd) cAGB | Addc d2 (eg) | 
 fded cAGE | F>(D (3EFG) A2 (AB) | c2 (cd) cAGB | Ad{e}dB{d} cAGE | F>(A (3GFE) D2 z || g | 
 fdeg fdec | Addc Addg | fdeg fdec | ABcd c2 (fg) | a2 (af) g2 (ge) | fgfe d2 dc | AddB{d} cBAG | 
 F>(A (3GFE) D3 |]  