I know that the standard answer is that a person can have more than one diagnosed mental illness due to meeting the criteria for each one, specifically.

But if you think holistically about a person and their mind, there seems to be just a niggling of a problem.

For instance,
I have been diagnosed at times of having GAD but I really do think my tendency to anxiety is part and parcel of my bipolar or sza, whichever it is. It's one way my illness can interfere in normal life.

I am also paranoid sometimes but not enough to meet a diagnostic criteria for another mental illness so my paranoia is just lumped in with being a symptom of bipolar.

To me the distinction between labelling anxiety as . a separate illness and not labelling paranoia as one is pretty arbitrary.

That's why I think it is just one mental illness that I have.