How to pre-filter dropdown via deluge when is a lookup from a different App?

How to pre-filter dropdown via deluge when is a lookup from a different App?

Please help with why we get errors when querying a form in another app.

In "APP2" we have some lookups that are from "APP1" (GREAT that Zoho can do this! :-)

In APP2, for the lookup APP1 --> Property, there are a lot of records, and we'd like to pre-filter this lookup, via a "choose_state" dropdown for selecting a single State, and an OnUserInput script that queries the records by that state and sets the UI dropdown.

(We've done these before and have no trouble with the details.  But never "across apps".)

(Note that we would not want to use the Form's "Set Filter" since that would be hard-coded, vs. the dynamic pre-filter based on user's choice of State.)

In testing to clear up the error msgs I have reduced things to their simplest form, AND commented out all other code so that any errors involve this one line alone:

When we don't specify the outside App, we get this error msg, as expected:
Form 'BizDev_Properties' does not exist in this application.
  1. make_proplist = BizDev_Properties [(ID > 0 )];
When we DO try to specify the outside App, We get this non-specific error:
"Improper Statement. Error might be due to missing ';' at end of the line or incomplete expression."
  1. // APPNAME SYNTAX AS THE FORM's URL
  2. make_proplist = the-link.BizDev_Properties [(ID > 0 )];
or,
  1. // APPNAME SYNTAX IS SAME AS DELUGE FORM DEF FOR FIELD
  2. make_proplist = the_link.BizDev_Properties [(ID > 0 )];

Hopefully we are simply using the wrong syntax when referring to the other app (in yellow above)?  Above are the 2 we tried.  As for the name of the form itself, it's deluge name (Form Link Name) is correct as "BizDev_Properties".

Hopefully, it is supported.  If we can USE a lookup from another DB we should be able to pre-filter it via deluge, right?

...yet, I found, in a different need, that the form scripting could NOT directly query the other app's DB, and we had to request the values as a LIST or MAP array sent by a function defined in the other app.  --But this would be unworkable in our need above, with such a large list.

Many thanks!