Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:F
['BAB GAB AcA FGA BAB', 'FGA EGF DFE CEF AGE GFD', 'EFD =B,FE GEC- CEF']  
X:1
L:1/8
M:6/8
K:F
[K:Cmix] GA | BAB GAB | AcA FGA | BAB G2 A | GEC CGA | BAB GAB | AcA FGA | BAB GcA | G3- G |: cA | 
 FGA EGF | DFE CEF | AGE GFD | F2 E CcA | FGA EGF | DFE CEF | AGE GFD | C3- C :: ED | EFD =B,FE | 
 GEC- CEF | AGE GFD | F2 E CED | EFD =B,FE | GEC- CEF | GEG FD=B, | C3- C :|  