lovezebs you sure sound like you've covered all the basis. Perhaps she is just very broody.
My canaries feed each other too. That is what the male is supposed to do to the hens as part of their pair bonding. If I recall correctly the males feed the hens while they incubate. I've not bred canaries, so don't quote me on that one.
If all looks good and she is just acting weird then I'd also not be too keen to dose them on any meds, though I do want to say that even indoor housed caged bred birds can pick up internal parasites like worms, so they can be dewormed annually. You don't need to do it as regularly as outdoor kept birds, but it would be good to do it once or twice a year as a preventative.
no way, no how, not happening! 
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