Next question, if she is so weak and undernourished, I suppose the kittens dont get enough, however heroic mom she is.
Are you giving some extra to the kittens? I suspect strongly you should.
The easiest way to know if they get enough is to weigh them every day. If they get 10+ grammes a day, it is OK.
Goat milk is good for kittens too. And possibly also for your bro. Quite a few humans who dont manage common cow milk, does manage nicely goat milk. :) Goat milk has also excellent nourishment values.
Ask your doc of course before you experiment with your bro.
About this power milk. It may perhaps be useful if enough desperate, I dont know, but why experiment if you can get hold on goat milk.
Add raw egg yolk in, if you dont have problems with salomonella in eggs in your country.
But dont raw egg white, there is some enzyme which is not good for cats. Boiled egg white is ok, but not raw.