Much as we want to, we can't help every cat in the world. What are the conditions in Chestnut Cat Sanctuary? Are they strictly no kill? If the conditions are good and they only pts suffering cats, at least you know that those two are in a safe situation, whereas the two your friend needs to rehome could end up at a rescue which has a pts policy and/or poor conditions.
The ones living close to you would adapt if kept in for a time, which you'd have to do with the Sanctuary cats anyway.
If you find it impossible to choose, try a trick of mine: toss a coin. If you want to do "best of three" then you know the coin didn't give you the answer your heart wanted to hear. On the other hand, if you're happy with the result of the toss, that was the answer you wanted.