Vin, I'm so sorry to hear your loved one is still having problmes with nausea and vomiting. I had some problems with that semi-regularly through October, which was about 5 months out. And still VERY rarely (maybe once a month) I have a problem.
For me, after the nausea of the chemo wore off, I think the main problem that triggered the vomiting (and still can) is phlegm caught in my throat right around where it triggers my gag reflex. I think this becomes more of a problme when you can't swallow your own phlegm easily (which is also true for me) and I still do a fair amount of throat clearing and spitting each day to prevent it building up in the back of my throat and making me queasy.
As others here have mentioned, after feeding with Jevity, I was (and am) a little more vulnerable to being queasy for about 1/2 an hour too. Until recently, I fed myself one can at a time using the syringe but just letting it go in from the syringe at the rate it wanted to--not using the plunger to push it in. Now I can do two cans at a time three times a day as well as a can late in the evening--basically it's more like having regular meals and my stomach seems to have adjusted quite well.
I also think the queasiness was aggravated a lot when I was on prescription painkillers. They totally killed my appetite and just made me way more vulnerable to nausea I think. I know when I went off those was also around the time it became very rare for me to get nauseated enough to vomit. I'm wondering why your loved one is still on such strong painkillers 8 months out. It seems to me if she could get off of those (which may unfortunately involve more nausea temporarily as she cuts down--you should definitely ask her doctor about how to do that, not just do a cold turkey thing), she might be way better off in terms of the nausea. She's also almost guaranteed to have more appetite which makes the whole tube feeding thing lots easier.
Nelie