Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/4=150
M:4/4
K:C
['G2 A2 _B2 d2 cA/_B/ A2- A>Bc>A', 'c>AB3/2 D/ D/E/^FG>A _B>cd>A _B<G A3 ^F']  
X:1
L:1/8
Q:1/4=150
M:4/4
K:C
 D | G2 A2 _B2 d2 | cA/_B/ A2- A>Bc>A | _B>AB<d c>AB>D | G2 A2 _B2 d2 | cA/_B/ A2- A>Bc>A | 
 _B>AB<d c>AB3/2 |: D/ | D/E/^FG>A _B>cd>A | _B<G A3 ^F G>A | _B>cd>d c/B/c d>B | 
 G>^F G/A/_B c>A^F<A | G6- G3/2 :|  