You should start to notice effects within a few days. You may also get the Botox ‘flu’, so be aware of that too - it might feel like Covid. A small number get generalised spread i.e. generalised weakness.
I completely understand why your sister in law needed to get away from some of the stress that MS brings to everybody involved with it. I get very frustrated with the way social care funding works, I feel that I am being punished, along with many others in the same boat as me, for working hard all my life and paying my way.
At the moment my big project is to get as many things changed over to being Alexa compatible as possible. I have the three main lights, and my electric heaters on Alexa, next I want to buy a smart TV which will use Alexa to switch it on off and change channels for me. I am constantly dropping the remote controls for the TV that I have which means I have to wait for someone else to appear and pick them up for me. I am also grateful that I can call numbers on my contact list of my phone if I need help, again I am constantly dropping my mobile phone Which is not ideal!!.
Yes I have two carers on each call for hoisting purposes. I had a through floor lift installed plus a ceiling hoist upstairs, you can see where my savings have been spent!! Downstairs I have a mobile hoist.
I am 69 and have had MS since I was approximately 19 years old, it was first relapsing and remitting but has now progressed to secondary progressive MS. This forum site is extremely good and you can get advice on all sorts of subjects to do with MS. Some of the regular members of the site are absolutely priceless in their knowledge and experience they have and will always offer to help.