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
['BdGA BGdB', 'G2 Bd g3 e', 'B2 GB']  
X:1
L:1/8
M:2/2
K:G
 BdGA BGdB | ADFG ABcA | (3Bcd GA BGdB | cAFG AG G2 | BdGA BGdB | AD D2 ABcA | GABd g3 e | 
 fdcA BGFA :: G2 Bd g3 e | f3 d ABcA | G2 Bd g3 e | fdcA BGFA | G2 Bd g3 e | f3 d ABcA | 
 dg g2 bgag |1 fdcA BGGF :|2 fdcA BGGA |: B2 GB B2 GB | A2 FA A2 FA | B2 GB B2 GB | cADF AGGA | 
 B2 GB GBdB | A2 FA dAFA | G2 (3Bcd g3 e | fdcA BGGA :|  