>>So the current solution with the two initial pieces staying welded inside the exe (caller grid, the form) and everything else (classlib, prgs with bizobjects, couple of small readonly dbfs) in the subfolder is the usable solution.

Our interfaces have prg classes inside the exe with localization in a prg outside the exe. The localizer prg contains a subclass definition and a single line to create an instance of that class.

Simplifying and removing status/error trapping etc, the subclassed/localized object is created by

loLocalizer="" && variable left in scope for...

do outsidelocalizer.fxp

if vartype(loLocalizer) !="O"
	loLocalizer=create("localizerbase")
endif
...
...
Define class localizerbase as custom
...
...

and in outsidelocalizer.prg:

loLocalizer=CREATEOBJECT("customLocalizer")
RETURN

DEFINE CLASS customLocalizer as localizerbase
...
...

That definitely works. So it might be worth moving the key class into a prg via classbrowser or whatever, then distribute your add-on fxp.