Copy a glyph from a character to another

[Etshy]

Hi.
I edit some font to add accent character.
I made an accent with a new glyph on a character and I managed to copy this "accent glyph" to another character.

But now I can't copy/paste it anymore. Is there a reason ?
Is there another way to quickly add accent (making one glyph "accent" and then use it on all the characters that need an accent) ?

I tried to make a separate glyph and then import it to a character but then I can't locally modify the glyph (like mirror it).

Let me know if I'm unclear on some point)

ps : I have the home version.

[Bhikkhu Pesala]

With the Home Edition, copying the accents to create composite glyphs (accented glyphs like Á, À, etc.)

To speed things up, copy several glyphs, then delete those that are not needed.

See Creating Composites in the Home Edition