I really hope that at least a few of the senior royals attend and don't snub Gabriella's wedding, like they did her brother's.
(I heard it was because they don't much like Princess Michael, and wanted to distance themselves from Freddy because of the press about his drug use.)
But Gabriella hasn't been involved in scandal (other then that very old article from her sleazy ex-boyfriend) and Tom Kingston is known to be discrete and very private.
I'm not sure how we are so certain the senior royals "snubbed" Freddie. Do we know if they were even invited? Are they even close to Freddie other than Eugenie? And I highly doubt they'd allow negative feelings towards Princess Michael, if any, to be handled like this. She is still invited to BP for Christmas lunch and Trooping every year. I doubt they have anything other than a cordial distant relative relationship.