Mi 11 Pro, Update to Miui 14, two partitions


Jan 22, 2023
Hello and thank you for the opportunity to find some help.
I am totally new in updating issues and therefore made some mistakes for which I hope you can give me some assistance.
I wanted to update a Mi 11 pro from Miui 13 to 14. I downloaded the ROM directly to the phone to \downloads (took some time).
The phone already prompted download available but was unable to download the file in the download section on the phone. But with the three dots I could choose a download package. I did this with the downloaded file. The update process started. It went to the TWRP and did something. When it was finished I went to "wipe", because I read some where, that a wipe could be good for a new rom. Bad mistake, it was an udate and not an new rom, but too late.
The system started and I had the new Miui, but my files where missing. In total the whole space was missing which was former occupied.
So I went back to TWRP. There in the browser I could see all my data.
So it looks for me like I have now two partitions. One with my old data and one with the operating system.
How could I merge both to one working system with the data?
Thank you.