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
['G3 GAB ABA ABd edd', 'dBA BAB dBG ABA AGA B3 dBd']  
X:1
L:1/8
M:6/8
K:G
 G3 GAB | ABA ABd | edd gdd | edB dBA | G3 GAB | ABA ABd | edd gdB |1 AGF G2 D :|2 AGF G2 A |: 
 B3 dBd | ege dBA | BAB dBG | ABA AGA | B3 dBd | ege dBd | gfg aga |1 bgf g2 A :|2 bgf g3 ||  