Balloon Fill Procedure

[ProfLeeT]

We are trying to determine with what force the balloon should lift. We have seen on the predict.habhub.org website Balloon Calculator that the Neck Lift value doesn't change when we change the payload mass. This means that the neck lift isn't accounting for our payload mass. 
For example, our payload mass was 1.5 kg and the neck lift states that it should be 4.5 kg using a 2000 g balloon going to 33km. What we logically think we need to do then is to add to this the mass of our payload (1.5 + 4.5 = 6 kg). Such that, when we fill the balloon and hang a force sensor from it, that the balloon is capable of lifting 6 kg of mass. Is this correct?
Is there a website or something that details this discussion so I can be certain? The Balloon Fill procedure document on the FAQ page was not super helpful in this department.
Thanks!

[Matt]

I have the same question.

[leviw]

It looks like the calculator has a bug in it when used from the flight prediction page. Here's the same neck lift calculator tool from the same site, but in a separate page.  The neck lift DOES update on this tool.

In case anyone's interested, we're having a discussion about neck lift and ascent rate in the google group right now.  The consensus seems to be to use that calculator instead of expecting a flat percentage to hold true for all payload or balloon combinations.