"and/or business account paid for her personal expenses."

And now they need to stop that nonsense. This shareholder formed a corporation, and this commingling of funds defeats that purpose. Yes, the shareholder might need to fund the corporation. No, the business never pays for personal expenses for the shareholder.

Is this the first year of these activities? If you net the two activities, do you have loan from the shareholder or loan to the shareholder?

You've used the phrase "open account" which is further indication she thinks this is her very own private bank. It's a separate and incorporated entity. Let's treat it as such.

That message is to flag you, and your shareholder needs to understand that the IRS requires imputed interest with this type of activity, because it isn't supposed to be treated so casually.

Google this:

shareholder loan over $10,000

And read a lot of the results