Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:6/8
K:G
['', 'BGG ADD', 'g3 f/g/af', 'd cAA ABc dge f2 d |1']  
X:1
L:1/8
M:6/8
K:G
 GA |: BGG Add | BGG ADD | BGG ADD | GBA G/F/ED | BGG AFF | BAG ABc | dge f2 d |1 cAF G2 A :|2 
 cAF G3 || GBd g2 e | fed cAF | GBd g3 | f/g/af g3 | f/g/af g2 e | fed cAF |1 B/c/BB BAG ||1 
 B/c/dB cBA :|2 f/g/aa gfe | d3 dcA || GBB B2 d | cAA AFD | GBB BAG | B/c/dB cBA | GBB B2 d | 
 cAA ABc | dge f2 d |1 cAF G2 G :|2 cAF G3 ||  