You've repeated your qn many times.... Maybe it's not that ppl don't understand the qn, but that you don't understand the answer?
A little understanding of incident light metering and zone system will put you right. Just google or wiki.
1. The incident light reading is the correct one to use. But there can be more than one incident reading to be made in a scene.
2. The fact that your highlights can still blow doesn't mean the reading is wrong; it's due to the dynamic range of your sensor. That's why in the film days, we said expose for the shadows and develop for the highlights. For slides and digital, we have to expose for the highlights, because the limitation on the medium is the highlights. That's why when shooting slides/digital you have to take an incident reading from the highlights while shooting negs one takes the incident reading in the shadows.
3. For a backlit subject, if we want the shadow detail, we can expose for it using the inicdent reading for the shadows, this will overexpose the background and blow it out. Again, this doesn't mean your reading is wrong, as above. However, the usual remedy in such situations is to fill flash so that you can bring the shadow exposure more in line with the highlight exposure, and hopefully reach an exposure where both do not blow out.