Help / advice needed with 3 stray cats.... Chelmsford, Essex

[Debburt]

I have 3 stray cats that visit my garden constantly, one for well over a year, the other 2 about 6 months... 2 are very friendly (the other one is extremely nervous). Of the 2 that will come to me.... One is a short haired tabby (male?), the other is a beautiful Maine Coon.... (not in great condition). We are out in the country so it could be they have been dumped??
I have my own elderly cat who is not friendly with others, so I can't really have more cats! And I'm moving in the next couple of months..... so I really need to make sure they're all ok before I go as I can't take them.
I have tried the Cats protection, have posted flyers, etc. The vet says to try and get them there to be scanned for a microchip which I will try and do this week.
Does anyone have any suggestions what the best thing to do is? I hate the thought of the winter coming and them being outside and cold and hungry
Thanks so much
Deb

[Kay]

do all three eat a full day's worth of food supplied by you? or is there a chance there is someone else feeding them too? strays often have a round of willing feeders they call on regularly, and if you think any or all of the three might be calling elsewhere, you could try to contact any fellow feeders

could they be farm cats rather than out and out strays? I feed two cats outside, and one, which is a full Siamese and I think neutered, takes all his/her food from me, and comes rain or shine, but the other, an unneutered tom, only comes by for food every few days, and I suspect is a farm cat supplementing his diet rather than being dependant on me alone