Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:A
['z B ceef ecBc ABcE FGAc Bffe', '', 'ac (3ccc ABce fgae ecAF EFAB']  
X:1
L:1/8
M:4/4
K:A
|: z B | ceef ecBc | ABcE FGAc | Bffe dBBA | GABc defg | aeef ecBc | fcec Aaga | fefd eagf | 
 ecdB A2 :| ag |: ac (3ccc ABce | fgae ecAF | EFAB cAfc | ecAc Befg | ac (3ccc ABce | fgae ecAF | 
 EFAB cefc | ecBc A4 :|  