Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/2=75
M:4/4
K:G
['G>GG>B d>ed>B d>gd>B d>ed>B', 'G2 g>gg>d g>dB>d g>af>g e>fd>e c>cc>A B>BB>G']  
X:1
L:1/8
Q:1/2=75
M:4/4
K:G
 G>GG>B d>ed>B | d>gd>B d>ed>B | c>dc>A B>cB>G | E>AA>G F>A A2 | G>GG>B d>ed>B | d>gd>B d>ed>B | 
 c>dB>c A>BG>G | E>GF>A G>G G2 || g>gg>d g>dB>d | g>af>g e>fd>e | c>cc>A B>BB>G | E>AA>G F>A A2 | 
 B>Gd>B g>dB>d | e>cA>c d>BG>B | c>dB>c A>BG>G | E>GF>A G>G G2 |]  