Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:E
['E2 EG', "b2 c'4 g3 b g2 e2 fg"]  
X:1
L:1/8
M:2/2
K:E
 (3B,CD | E2 EG FE C2 | EFEC B,2 C2 | E2 EG F2 [GB]2 | [Gc]4 [Gd]3 c | B2 G2 BcBG |[M:2/4] F2 EF | 
[M:2/2] G2 EG E2 D2 |1 E3 E E2 :|2 E8 |: b2 bb b2 gb | c'b g2 e4 | b2 bb ga b2 | c'4 g3 b | 
 g2 e2 fg e2 | cdec B2 EF | G2 EG FF D2 |1 E8 :|2 E6 ||  