Quick way to add groups of students

I wish there was a quick way for me to enter a group of students myself, to make sure they all use standardized username and password formats.

For instance, we use our school “alpha-key” (something like hoffmjam001) for the username, and a password consisting of “Nic#” plus their 5-digit ID number (like Nic#12345). If I could put these into a spreadsheet and just upload that, it would save me a lot of time, because I now enter each of my 80-some students individually, cutting and pasting from my spreadsheet.

We want the students to use these standardized formats because, if left to their own devices, someone (more like 7-10 people!) always forgets what they used for one of these fields, and it delays class progress while we get them straightened out.

I know that, theoretically, the students should sign themselves up using the join code, but anyone that has tried to get a group of students to do all the same general thing at the same time knows it’s like herding cats - and I teach high school students (I can’t imagine doing this with younger grades!).

Thank you!