Lady Gabriella Marina Alexandra Ophelia Windsor is following in Meghan Markle and Princess Eugenie’s footsteps. The royal bride-to-be, whose nickname is “Ella,” is set to wed her fiancé Tom Kingston at St. George’s Chapel, Windsor Castle on Saturday, May 18, 2019. Ahead of the nuptials — which will mark the third royal wedding at the venue in the span of a year — we’re taking a look at Queen Elizabeth’s relative…