Stop a lookup field being modified in the child table when it is modified in the parent table?

I've never used snapshot before but have heard of it. Interesting. I realize there is something that complicates things though....

What if I have a field that is not a lookup but is just a regular field. How could I snapshot that as well?

Typically you limit editing if specific field in a form using Dynamic Form rules.

Alternatively you can use Role permissions of you want to prevent editing of the record entirely under certain conditions.

np
Change the name of the [Day Rate] field to be called [Day Rate (lookup)]

Then make a new field called [Day Rate] and set that to be a snapshot field of the [Date Rate (lookup)] field.

ie the snapshot field is a separate field from the lookup field.