Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:A
['agae agae', 'a3 e dcBA cAce dcBA GBBe dcBA']  
X:1
L:1/8
M:2/2
K:A
 e | agae agae | dcBA GBBg | agae agae | fefg a2 (3efg | afge fdec | dBcA GBBd | ceAe dfBa | 
 gefg a3 |: e | dcBA cAce | dcBA GBBe | dcBA cAeA | fAgA a3 :|  