> ... in unstructured, regular 'ol FM.

FM what? I only have FM7 at hand at the moment, and it has no special features to generate Glossaries.

How are you creating the Glossary?

> ... is there a way to make the glossary alphabetize when I update the book?

If the G were done as a table (Col1:term, Col2:Def) in a non-generated file, you could manually sort the rows. Caution: test this before deploying, as FM has a tendency to delete any Xref Markers in table when sorting. Apparently, it sorts by Copy-Paste-Delete rather than Cut-Paste, and Copy in a table does not contain any Xref Markers present in the source row.

I typically do G's as ordinary Flow A text. The Term is a run-in PgfFmt, entered in alpha order as created. The Def runs into it. All instances of the Term elsewhere in the document are Xrefs by Paratext to the Term. If the Term changes, the document is auto-updated, but the Term/Def might have to be moved by hand in the G.

What are you entering for Marker Text?

The term and its definition?

Are you using any Building Blocks?

Are you electing

[*] Create Hypertext Links

Does FM10 have any other options for Glossary markers or LOM(sorted) gen that might not be in FM9 or earlier?

I just tried, in FM9, generating an AML that I wanted to end up looking like:
TERM: definition

using <Bold> (a defined ChFmt) and <Default Para Font> (per the manual), but these end up in the AML as plaintext instead of being applied.

Didn't work as <$Bold> or <Default ¶ Font> either.

Historical traffic on this topic suggests that G markers are not terribly useful, as the formatting is limited, and you can't easily turn every instance of the term in the narrative into a link to glossary.

People have also discovered that doing a Glossary as a table retains sort, but runs into the long-standing destroy-Xrefs-on-sort defect.

And doing my run-in-head hack creates a sorting problem for translators.