Craft a piece of music that integrates both the suggested theme and letter-based structure.
X:1
L:1/8
M:2/4
K:A
['GA FC EF AB cB BA', 'BA cB AE']  
X:1
L:1/8
M:2/4
K:A
 G | GA FC | EF AB | cB BA | Bc e2 | GA FC | EF AB | cB BA |1 B3 c :|2 BA/B/ c2 || z (f f)c | 
 ef BA | cB AE | FB B2 | z (f f)c | ef BA | cB AE | GA F2 | z (f f)c | ef BA | cB AE | FB B2 | 
 af fe | fe cB | AF FE | F3 ||  