Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:Amin
['E (EA)AB (cB)Bc BGDC B,A,G,B, (A,A)cB (Ac)ea', 'Aa^ga ea^ca Bgdg BGGB']  
X:1
L:1/8
M:4/4
K:Amin
 E | (EA)AB (cB)Bc | BGDC B,A,G,B, | (A,A)cB (Ac)ea | gedB cAA :| B | Aa^ga ea^ca | Bgdg BGGB | 
 Ga^ga ea^ca | gedB cAAB | Aa^ga ea^ca | Bgdg BGGB | ABcA Bcd^f | gedB cAA ||  