Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:Amix
['e2 de', 'fdcd eaae aeea gedB BAAA a2 ag']  
X:1
L:1/8
M:4/4
K:Amix
 e2 de AAAB | g2 fg BGBd |1 e2 de edea | gedB BAAA :|2 e2 ce ecea | gedB A3 e |: a2 ag aeef | 
 gage fdcd | eaae aeea | gedB BAAA | a2 ag aeef | gage fdcd | eage edea | gedB BAAA :|  