Hiyaaa
Sometimes it's suuuuper scary to share new things I totally get it!
I tend to write out what I want to say or make a little list of the important points to me so I have a guideline.
If talking immediately about the kink relating to /you/ is a bit much at first, I also just talk about the kink on it's own. Asking if your daddy knows about this kink and what it means to him/ it means. Then talking about what he thinks of it and bringing up what you think of it can be a bit easier to slowly introduce it?
idkkk to be honest I'm a scaredy cat so I'll just link a porn with the kink in it and be like lookie what I saw what do you think of that?