If the mother comes close enough to you to get food, would you be able to catch her by the scruff of the neck. She will panic but if you get her in a carrier then all you have to do is pick up her babies. Once they are all together she may relax.
If you can not get her, the other option is to just keep feeding her and giving her water. eventually she will trust you and so will her babies...
And I don't think changing her location at this point will make her life any worse than it is now. She is basically starving, I think change of location att his point sound good.