Sorry for the long post.
My partner's daughter in law has a 5 year old, and a 2 month old baby. They live in a HA flat on the third floor. The lift has been out for two years. The lady has severe type 1 diabetes, and has now hurt her back, plus she had a cesarean so that knocked her back too. Husband isn't always able to help, as he works odd hours. To get the little boy to school, she has to carry baby downstairs go to their car (hubby has work van, she's not allowed to drive) get the buggy out, and walk three quarters of a mile to school. She's just about done in. I wish I could help, but I'm disabled myself, and simply can't. I can drive them to/from school, but that's not the hardest bit. I suggested that if she carried baby up/down stairs in a sling it might help having hands free to hang on to the banister. That's all I can think of. HA are crap at rehousing them, so no joy there.
I want to buy her a carrier, but one that is really easy to put on/take off, isn't heavy, not a sling, and is there one that gives mum back support too?
My own dd is 37, so I'm really out of touch.