Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:A
['(c/d/) eaf e2', 'A2 A G2 A (B2 e) A2']  
X:1
L:1/8
M:6/8
K:A
 (c/d/) | eaf e2 (c/d/) | edc B2 (A/B/) | cfe dcB | AGF E2 (c/d/) | eaf e2 (A/B/) | cde f2 a | 
 ecA FGA | EAB A2 :: A | G2 A (B2 e) | A2 B (c2 e) | B2 c ^def | e2 ^e f2 g | aga edc | f^ef dcB | 
 AGF (Ee)d | cAB A2 :|  