Aw, Katie -- don't get down on yourself for this bc not one bit of it is your fault! You absolutely deserve their love, you're clearly a great Mum
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Kazzy gave some good advice, and that is probably worth a try.
Have you tried sprinkling Parmesan cheese on their food, which can really entice dogs? What about rotating the food (ie, kibble, wet, homecook, raw) so they don't get the same thing except for maybe a couple days in a row? Have you tried Natures Logic kibble yet...they have a certain thing they do for palatability...might be worth a try.
Are they related to each other, btw? If not, how odd that you ended up w/ 2 picky fluff butts!!!