Hi Harry,
Welcome to the site. Sorry that you had to find us all but am glad that you have joined in with us all as you will get a ton of support and help from all of us. So please, feel free to ask any questions that you have and we will all do what we can to help in answering them.
We have an excellent chemo board containing many posts from the members here who have shared their experiences of various types and combinations of chemo, and indeed many of the members have and are on the Gem?Cis combo that your mum is on. Using the search forum function at the top of the page will throw up many discusions that may be of interest to you.
Did your mum seek a second or even or third opinion on her CC and what treatments may be available to her? From what you have said, it sounds like your mum has a lot of support around her and that is great, and you also now have a lot of support around you here. I look forward to hearing more from you.
My best wishes to you and your mum,
Gavin