Colorado

The FBI has its own reasons for arresting and laying charges in its own time.

So, by actual reasoning, the fact that they have not announced an arrest does not mean that they have not "identified her as Borbert's mother".

Nonsense. You have no facts or logic to back up such a bald statement. In reasoning, absence of evidence (arrest) is not evidence of absence (absence of guilt). For example, just because Mueller didn't indict tRump doesn't mean that he wasn't indictable (that's a legal controversy). Nor does it mean that there wasn't enough criminality to indict him. Probably Mueller didn't dig deep enough.

One factor that could easily play into a delayed arrest/announcement is one that would occur to many Democrats in this weird period just before tRump leaves office. It is entirely possible that the FBI / DAs etc do not want to give tRump a flag to pardon a high profile arrestee just right at the moment.