Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/2
K:A
["c>d e>^de>c a>ga>e c'>bc'>e a>ga>e |1 f>gf>e", '(3fed c>Bc>A', '(3edc B>AB>d (3gfe (3dcB A>ce>f']  
X:1
L:1/8
M:2/2
K:A
"^A" | c>d | e>^de>c a>ga>e | c'>bc'>e a>ga>e |1 f>gf>e d>cB>A | (3EGB (3egb e'2 :|2 
 (3fag (3fed c>BA>G | B2 A2 A2 |]"^B" |] B>c | d>cd>B (3bag (3fed | c>Bc>A (3agf (3edc | 
 B>AB>d (3gfe (3dcB | A>ce>f e2 |]  