Sorry I missed the source of confusion. Hopefully I can clarify (sometimes I fail).
1. When you set up the ONAG you make the guider parfocal to the camera/ filterwheel combination. Usually using the Lum filter.
2. Focuslock uses the guidecamera image to determine what side of focus you are on. Note the the ONAG is using the same field of view as the imaging camera, it is just using the IR portion of the spectrum.
3. Focuslock moves the focuser to achieve focus of the guidestar and because this is parfocal with the imager it is also focusing the light for the imager simutaneously.
Ths works well for the filter for which you established parfocal"ness" but not other filters that are not parfocal.
To deal with offsets Focuslock can be set up to change what it considers "focus" to be for the guidestar. Because the system knows which direction it is out of focus it knows exactly what it's offset is from focus (either inside or outside).
You can set the filter offsets on Focuslock by focusing your camera with the filter in question and then tell Focuslock that this position is the focus point for the filter in question.
This only works if there is someway to tell Focuslock what fliter is currently in use bu the camera. Right now the system works fine "dumb" because I am taking a hit on my focus points for the filters that are not parfoal with my Lum filter.
Hopefully this helps...it may not...best. Tim