shanuea
Let me elaborate on Georg’s suggestion:
- Go to the Font tab.
- Select a-z.
- Delete them by hitting Cmd-Delete. Confirm the dialog.
- Choose: Font > Add Glyphs (Cmd-Shift-G)
- In the appearing dialog paste this:
A=a B=b C=c D=d E=e F=f G=g H=h I=i J=j K=k L=l M=m N=n O=o P=p Q=q R=r S=s T=t U=u V=v W=w X=x Y=y Z=z - Confirm by clicking OK.
Now your lowercase letters consist of uppercase component, i.e. if you change the original uppercase letter, the lowercase will change too. I think that’s the better solution for what you want to do.