Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/2=72
M:4/4
K:Dmin
['FG A3 c AcGA F2 c2{d} c2', 'f3 g']  
X:1
L:1/8
Q:1/2=72
M:4/4
K:Dmin
"^Slow" FG | A3 c AcGA | F2 c2{d} c2 BA | (GFG).A BAGF | D2 d4 cd | f3 g agfd | (cA)(cd) f3 F | 
 (GA)(fd) c(ATG>F) | D2 d2 d2 :: cd | f3 g fgag | f2 a2{b} a2 Tgf | gfga (ba)(Tgf) | d2 ga g2 fd | 
 cdfg (ag)(fd) | cAcd f3 g | (ag)(fd) cATGF | D2 d4 :|  