Hate to be that person but make sure your brother wasn’t in on all this.

any chance you have camera footage from that day?

Can you place him on paid leave with a directive that he needs to see a medical professional before he can return?

My father’s business lost 100k when a client company turned around and filed bankruptcy. That nearly cost him his business.

Lots of good suggestions. Maybe you can hire the extra person first and see if that pans out. If it doesn’t then you’ll have to lay them off or just not rehire if they leave at the end of the following year. Small risk for moderate gain