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
['G2 G BAB cBc def gfg', 'dGB cde cAB', 'dGB cde cAB']  
X:1
L:1/8
M:6/8
K:G
|:"^A" D | G2 G BAB | cBc def | gfg edc | BAG FED | G2 G BAB | cBc def | gfg ABc | d3 d2 :| 
"^B" B/c/ | dGB cde | cAB cBc | dGB cde | cAB c2 d | e2 d eaf | g3 gfe | dcB AGF | GAG G2 || 
"^C" B/c/ | dGB cde | cAB cBc | dGB cde | cAB c2 d | (2:3:2ed e3 | (2:3:2ea f3 | (2:3:2ga g3 | 
 (2:3:2gf e3 | (2:3:2dc B3 | (2:3:2AG F3 | (2:3:2GA G3 | G3- G2 ||  