London (CNN) -- Apart from the Windsors, there are two other blue-blooded families at the heart of Kate and William's wedding -- the Spencers and the Parker Bowles.
The Spencers are the late Diana, Princess of Wales' clan and number among them Prince William's aunts, uncles and first cousins.
While the Parker Bowles are the kin of Camilla, The Duchess of Cornwall, Prince Charles' second wife.
More than a decade after Diana famously said "there were three of us in this marriage" of Charles' illicit relationship with Camilla, are there still tensions between the two families?
Who are the key members on each side? Find out with our guide to the Spencers, Diana's family, and the Parker Bowles, Camilla's clan.
Brother of the late Princess Diana. He has a way with words, as he proved when giving the oration at his sister's funeral. The speech was regarded by many as less than complimentary towards the royal family. The earl also has a way with the ladies -- this June he'll be hoping it's third time lucky as he weds charity worker Karen Gordon.
Lady Kitty Spencer
First cousin of Princes William and Harry, niece of Princess Diana and daughter of Earl Spencer from his first marriage to model Victoria Lockwood. The good genes show: She was described as a "blonde bombshell" by Tatler magazine when she appeared on its cover two years ago.
Lady Eliza and Lady Amelia Spencer
Twin first cousins of Princes William and Harry, nieces of Princess Diana and daughters of Earl Spencer. They live with their mother Victoria Lockwood, the earl's first wife, in Cape Town -- where Lady Amelia was recently reported to be involved in a fight at a McDonald's.
Louis Spencer, Viscount Althorp
First cousin of Princes William and Harry, nephew of Princess Diana and son of Earl Spencer with his first wife Victoria. Heir to the Earldom.
Baroness Jane Fellowes
Aunt of Princes William and Harry, older sister of Princess Diana. Married Baron Fellowes in 1978, with Diana as bridesmaid. The baron was formerly private secretary to the Queen.
Lady Sarah McCorquodale
Aunt of princes William and Harry, eldest sister of Princess Diana. She was president of the princess's memorial fund, which attracted controversy over its unsuccessful legal battle against a company that brought out a Diana doll. Married Neil McCorquodale in 1980 and has three children.
THE PARKER BOWLES
Andrew Parker Bowles
First husband of Camilla, Duchess of Cornwall -- current wife of Prince Charles. An army brigadier, he married her in 1973 and they had two children, Tom and Laura, before divorcing in 1995.
Tom Parker Bowles and Sara Buys
Stepbrother of princes William and Harry, stepson of Prince Charles and son of Camilla, Duchess of Cornwall, from her first marriage to Andrew Parker Bowles. Educated at Eton, he made wince-inducing headlines for his family when he was exposed for taking cocaine -- prompting Charles to give him a stern talking-to. He's since redeemed himself with a career as a food writer and role at concierge company Quintessentially. Married Sara Buys, fashion journalist, in 2005.
Laura and Harry Lopes
Born: 1978 and 1977
Stepsister of princes William and Harry, stepdaughter of Prince Charles and daughter of Camilla, Duchess of Cornwall, from her first marriage to Andrew Parker Bowles. She studied history at Oxford Brookes University and manages an art gallery. She married underwear-model-turned-accountant Harry Lopes in 2006 -- the first family wedding that Kate and William attended together. Their three-year-old daughter Eliza is bridesmaid to Kate.
Nephew of Camilla, Duchess of Cornwall and son of her sister Annabel. Eton-educated co-founder of concierge firm and private club Quintessentially, whose members range from his aunt to hip-hop mogul P. Diddy. Was best man to cousin Tom Parker Bowles at his wedding. Has a sister, Katie.