How do I use SQL in Btrieve v6.15 with Titan Btrieve?

I'm doing some work for my company on a Btrieve v6.15 with Titan
Btrieve 3.0d in Delphi 3.

I need to use nested SQL statements to limit the range of each field
in a multitable join. I can not upgrade or change the Database or
compiler.  Does anybody have a clue how I can do this?

The manual for Titan indicates that Tquery can not be used. Yet there
is a Ttbquery, but I could not get it to work either. I got the
DBIERR_NOTSUPPORTED error message.

Any ideas would be appreciated.

Sourena Mansouri