Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/16
M:2/4
K:G
['G2(FE) D2(FD) (AD)(FD) B,E2F G2A2', '(BG)E2 B2{c}(BA)']  
X:1
L:1/16
M:2/4
K:G
 vB,uE2uF G2(FE) | D2(FD) (AD)(FD) | B,E2F G2A2 | B2(3(cBA) (BG)E2 | B,E2F G2(FE) | 
 D2(FD) (AD)(FD) | B,E2F G2A2 | B2(3(cBA) (BG)E2 |] B2{c}(BA) (Be)e2 | B2{c}(BA) (BG)E2 | 
 B2{c}(BA) (Be)(ef) | (ge)(f^d) e4 | B2{c}(BA) (Be)e2 | B2{c}(BA) (BG)E2 | B2{c}(BA) (Be)(ef) | 
 (ge)(f^d) e2 z2 |]  