In all my years, never had fussy eaters either..... dogs..... not wanting food,

so strange. :-D
Well, it's not all bad......your's seem to like the meat, which is a good thing, seems they are being more picky than not being hungry at all......just not over keen on the kibble sometimes and are having it as a last resort?
Have you tried soaking the kibble in warm water until soft and then mixing in the tripe, or even adding gravy, another trick is to squash it into mince meat, that might make them eat it. Looks like they would prefer a BARF diet. :-D
I'd definitely, be giving chicken wings to plump up, especially the white bitch if she is losing fast, some dogs just do not get on with kibble, I couldn't bare to see a dog losing weight, I'd be out getting those wings.......
Hoping this is sorted soon........