We have no idea, other then those who have spoken to the press. And these were ones who spoke to the press before the invites went out. Her dad's two brothers, Fred (bishop) and Michael (former ambassador), his kids Samantha and Tom Jr, Tom's kids, and Doria's older half sister and brother.
But who we don't know about:
-Joffrey Ragland-her 34 year old half-Uncle, Doria's paternal half-brother
-Ava Burrows- Joffrey's mother, Meghan's step-grandmother
-Ashleigh- her lawyer niece
-Christopher- Ashley's brother, the only nephew who hasn't spoken
-Noelle- Ashleigh and Christopher's younger half-sister
As they don't speak to the press, we will likely not know until the wedding. I assume Ashleigh and likely Christopher at least will accompany their grandfather.