Trying to add a spell to a familiar
 

I'm making an NPC, but i can't see where i might be able to add a spell-like ability to her Familiar!

She's an Eldritch Knight crime-lord with the Magic Initiate feat and i'm tying all those spells to her Infernal Cat. The cat isn't supposed to be your average familiar. She has a few spell like abilities (Misty Step, etc...).

I can't see anywhere in the personal tab on the familiar to do this.

If I were doing this, I'd make a new monster for the familiar in the Editor. Take whatever cat you are going to use, and make a new copy of it. From there you can add the abilities to the new cat. There *may* be an extra step to get Hero Lab to recognize the new monster as a valid familiar, but I'm not sure off the top of my head if it's just a field on the monster (that would already be checked if you're copying an existing familiar) or some field in the Find Familiar spell itself that needs to be extended.

If I remember correctly, when you create a race (creature), on the far, upper ring of the scrolling window, you will find a check box that gives the creature the option of being a familiar.

There is a checkbox in the second/third column in the editor for whether a monster is a familiar.