I can confirm that if you purchase them from NorthShore Care Supply's Amazon store they ship them using plain boxes, that is how I obtain all of my refills.
They also usually include one or more samples of either a small package of their sanitary wipes, two of their brand diapers, or two of their booster pads. Most often they seem to include the diaper sample which is nice because you are basically getting an extra two briefs (Of their own brand) thrown in for free. Their briefs are also quite good as well, nearly on par with the Abena briefs in my opinion.
If you're looking at the cases, none of them are fulfilled by Amazon. I have ordered one case from there, the one from Abri-form, and an "abri-form" label did appear on the box, but it didn't scream diapers. I'm not too concerned about this, as I order it to be shipped on days I know I will be alone and it didn't scream diapers, but I would take this into consideration.