Hi Sharon. I answered you on a previous post today, but just in case you didn't get it, I'll write again. Older cats are definitely harder to tame as they are more set in their ways and have decided that they don't need human interaction to survive. At this point, I don't think she'll ever be a lap kitty for anyone but I think you've gotten her to a point where she would stick around someone's house if she were getting fed. But as you said, it's coming on winter, so that option may be out for a bit until warmer weather comes again.
In the meantime, you can try withholding food for a day and then trying to hand feed her some treat like hot dogs or canned food and see if she's okay with that much contact. I know that she hasn't been an extremely food driven kitty, but if she gets just a little hungry, she might be more interested.
You can also try introducing her to another kitty, as long as they are both comfortable with it. I know your other cat hasn't been a huge fan in the past, so she might not be the one to use. If you could 'borrow' a very friendly kitty that could show her how much they trust people, Blackie might follow along.
I do think an outdoor home would be best suited for her and make her the most comfortable. If none of the suggestions above work for her, you could consider acclimating her to the weather and finding an outdoor home for her. You can acclimate her by putting her in an unheated garage for a couple hours at a time. Continually build on that amount of time. An open wire cage would be the best so that she can see her surroundings.
If you are able to find her an outdoor home, have her spend time in their garage or outbuilding and make sure they provide a comfortable shelter and food for her.
I hope this helps. Sorry I don't have any more great suggestions but I hope one of these will work for you.
Thank you and good luck!