It is kind of useful that you can just type a bunch of terms into the tag box separated by commas and click the “add” button just once as opposed to having to click it once for each term. However this comes with a down side, you cannot user tags (or any custom taxonomy that works as tags for this matter) that contain commas in themselves.

Let’s say for example you want to add a tag such as “Einstein, Albert”, no matter how you try this WordPress will add two different tags, “Einstein” and “Albert”.

So how do you then add tags with commas within themselves? You just can’t, that is without applying a little trick at least. The trick works as follows:

Instead of commas in your tags use any other symbol or a combination of them, a weird one if possible, something like a double dash “– “ for example, so something like this “Einstein–Albert” and then add a function to your functions.php file that will filter that string and replace it for a comma before displaying it.

Here is the function that will do that for you:

Now simply replace “authors” with your custom taxonomy slug on line 3 and also replace all instances of “- -” if you are using any other character screen instead of the commas.