After which, more than 2,500 members of the public will help celebrate the big day.
Samantha Markle, 52, reacts to the facts that Meghan is inviting "complete strangers" but "no one" from her own family was invited.
"Out of respect and humanitarianism, the Markles should be invited if 2,000 complete strangers are," she posted on her twitter.
"Our uncle, brother, me, best friend of 30 years, nephews. At issue is not a matter of closeness. Family is family."
Prince Harry's fiancée remains close to her dad Thomas Markle, even though the 73-year-old lives a quiet life near Rosarito in Mexico - but it's unclear whether he'll walk his daughter down the aisle.
Meghan's mum Doria is expected to attend - she joined the royal couple at the Invictus Games last year.
