Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:D
['dfec A2 AB', 'd2 (fd) adfd', 'd2 defg afge cdef g2 fg (3(agf)']  
X:1
L:1/8
M:2/2
K:D
|: dfec A2 AB | cdef{a} gfge | dfec A2 AB | cBcG TED D2 :| d2 (fd) adfd | c2 (ec) gcec | 
 d2 (fd) adfd | eaTag ed d2 || defg afge | cdef g2 fg | (3(agf) (3(gfe) fded | ea{b}ag ed d2 |]  