Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:Emin
['Be e2 efge', 'A,CEG GFDB, G,B,EF GGEC A,CEG FEDF']  
X:1
L:1/8
M:4/4
K:Emin
|: Be e2 efge | fdef gfed | Be e2 efge | f2 e^c dcBA :| FGEC A,CEG | GFDB, G,B,EF | GGEC A,CEG | 
 FEDF DEEF | G2 EC A,CEG | GFDB, G,B,EF | GGEC A,CEG | FEDF DEEF ||  