Hi Anton!
I've tried your first suggestion, but doesn't work and I can't find the cause.
See what I'm doing:

----- test.hhp -----
[OPTIONS]
Compatibility=1.1 or later
Compiled file=Test.chm
Default Window=Principal
Default topic=test.htm
Display compile progress=No
Error log file=test.log
Language=0x416 Português (Brasil)
Title=Test

[WINDOWS]
Principal="Test",,,"test.htm",,,,,,0x2000,,0x3006,,,,,,,,0


[FILES]
test.htm

[ALIAS]
HH_test=test.htm#Campo1

[MAP]
#include test.h

[INFOTYPES]

----- test.h -----
#DEFINE HH_test 1500

When I compile I receive the following warning: HHC3015: Warning: An alias has been created to "test.htm#Campo1" but the file does not exist (that I ignore like suggested).
When I press F1 (at runtime) I receive the following error: HH_Help_Context called without a [Map] section

I'm using HTML Help Workshop 4.74.8702.0