Is there a way to auto populate characters in glyphs?

Hi, I am new to glyphs, and I want to know if there is a way to autopopulate certain character sets using the single letters I have already designed. I’ve noticed in my font that it has automatically generated some characters for me, such as ‘aacute,’ but it hasn’t done the same for others, like ‘bacute,’ even though I have already designed their individual characters.

Yes. Glyph > Create Composite. And look into the Diacritics tutorial.