Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:D
['D D2 E/F/ G2 F/G/ A2 E/F/']  
X:1
L:1/8
M:6/8
K:D
 D | D2 E/F/ G2 F/G/ | A2 E/F/ G<AA | B2 A/G/ c>AF | G2 F/D/ =C2 D | D2 E/F/ G2 F/G/ | 
 A2 E/F/ G<AA | BAG cAF/A/ | GFD D2 A | ABc d2 d | =cAF GFA/A/ | ABc dcd | =c<AB c2 A | 
 AB=c d2 d/d/ | =cAG FGA | cAF G<AA/G/ | GFD D2 |]  