Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:4/4
K:G
['g e/e/e eg (e2 e)d/B/ BA AG/A/', 'g2 BA BAAB']  
X:1
L:1/8
M:4/4
K:G
 g | e/e/e eg (e2 e)d/B/ | BA AG/A/ BAAB | d>e (d/e/d/)B/ d2 Bg | BGG>A BGG :: d | g>ab>g a>e g2 | 
"^tr" BA AG/A/"^tr" BAAB | d>eg>a e>gdg | B<GGA BGGd | g>a (b/a/).g (gg/).e/ g2 | 
 BA A"^tr"(G/A/) BAAB | d>ega egdg | BGG>A BGG :|  