Why does my chocolate seize when I add brandy to it?
My guess is that you're adding the brandy cold, and the chocolate may also only be partially melted.  Try:


Ensuring that the chocolate is thoroughly melted;
Heating the brandy first (to just below boiling);
Gradually adding the chocolate to the brandy (not vice versa).  Chocolate seizes the worst with small amounts of liquid, so you're doing the opposite, adding a tiny amount of chocolate at a time to a relatively large amount of liquid).