Partition iMac 4TB SSD to Share w/ Spouse

[jedome]

I want to give my wife my 2017 iMac that has a 4TB SSD drive but keep all my photos, docs, etc. that are stored in it by partitioning the 4TB drive so she can then install what she has in her older, failing iMac. Then she would use my iMac as her computer (with my stuff just stored on it for access when needed). This then would allow me to purchase a new 2023 24" iMac M3 for my own use in photo editing & all else. A question also exists as how I get everything that is on my 2017 iMac onto the new M3 iMac before or after partitioning my 2017 iMac for my wife to use? Could I take both my 2017 iMac and her older iMac into the Apple store when I purchase the new M3 iMac for them to accomplish this for me as part of the setup for the new machine?