Hi there @BROOKEBREI ,
You're able to see in the top-right hand side of the page that grades on the page were modified by your student if they submit you a screenshot, and you'd be able to address it that way.
When it comes to entering in the SIS gradebook, I know there are some schools that have their SIS synced to Canvas, and it will automatically update in the SIS overnight from Canvas. Would your school by chance have anything like that set up? Now, this can also vary from institution to institution with rules, but I know some teachers that don't use the Canvas gradebook, they just review the assignment on Canvas and put the grade right into their SIS.
You can also have the students just take pictures of the score from the assignment's page itself, instead of from the grades page where they are able to change them themselves.
Do any of these sound like possible solutions?
Noah