Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:6/8
K:Gmin
['B2 G A^FD', 'fgf fcA']  
X:1
L:1/8
M:6/8
K:Gmin
 A | B2 G A^FD | B2 G A^FD | =F2 F F2 c | F2 F F2 c |{G} B2 G A^FD |{G} B2 G A^FD | 
 [B,G]2 [B,G] [B,G]2 d | [B,G]2 [B,G] [B,G]2 :| A | Bcd cBA | BAG AFD | fgf fcA | fgf fcA | 
 Bcd cBA | BAG A^FD | gag gdB | ga^f gdc | Bcd cBA BAG AFD | fgf fcA | fgf fcA | Bcd cde | 
 dcB cBA | [G,G]2 [B,G] [B,G]2 d | [B,G]2 [B,G] [B,G]2 ||  