Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/8=120
M:2/2
K:D
['F3 GEEG']  
X:1
L:1/8
Q:1/8=120
M:2/2
K:D
"D" F3 A"G" GEEG |"D" FDDF"A" ABAG |"D" F3 A"G" GEEG |1"D" AF"A"GE"D" FDDE :|2 
"D" AF"A"GE"D" FD D2 |:"D" Adde dcAB |"A" AGFG ABcA |1"D" d2 de dcAB |"C" =cBAF G2 FG :|2 
"D" d2 fd Adfd | d2 fd"A" e^cAG |]  