Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:2/2
K:G
['GBdg egdB GBdg (3(efg)', 'dg (3(gfg) bg (3(gfg) dgfg']  
X:1
L:1/8
M:2/2
K:G
 D | GBdg egdB | GBdg (3(efg) (dg) | eAcA eAcA | cdef gedB | GBdg egdB | GBdg (3(efg) (dB) | 
 cdef gedc | BGAF G2"^1)" z2 || dg (3(gfg) bg (3(gfg) | dgfg (3(efg) (df) | eAcA eAcA | cdef gedB | 
 dg (3(gfg) bg (3(gfg) | dgfg e2 (dB) | cdef gedc | BGAF G2 z |]  