Pippa Middleton
Pippa Middleton, sister of Catherine, Duchess of Cambridge, poses for photographers to promote her first book "Celebrate", on the subject of party planning, in London October 25, 2012.Reuters

Duchess of Cambridge Kate Middleton's sister Pippa will walk down the aisle on May 20 and Prince George and Princess Charlotte will have important roles to play in their aunt's nuptials.

According to a Daily Mail report, Prince George and Princess Charlotte will be page boy and flower girl respectively when Pippa and her fiancé James Matthews wed at the St Marks' Church in Englefield, Berkshire, on May 20. Their wedding ceremony will be followed by a reception at the Middleton family home in Bucklebury, which is a few miles away.

As for the wedding guests, reports indicate that it will be an intimate affair with just close friends and family . Pippa is expected to be dressed by trendy designer Giles Deacon, however, there hasn't been any confirmation from the Middletons.

Shortly after Pippa's engagement was announced, it was reported that the Duchess of Cambridge wasn't happy with the alliance, mainly due to James' brother Spencer, who is a reality television star.

"[Kate] is horrified about Spencer being Pippa's brother-in-law," a source told Life & Style back in August. "Spencer has slept his way around London and left a lengthy trail of angry women in his wake," a different insider revealed. "Kate's concerned. The last thing she wants is for William's family to turn against her because of Spencer's actions."

Spencer is a former star of Made In Chelsea and the British version of ABC's hit dating reality show The Bachelor. He is known for his womanizing ways and he once told a girlfriend on the show that it was hard to respect her when she allowed him to cheat. He also revealed intimate details of his sex life in a 2014 tell-all memoir titled Confessions of a Chelsea Boy. In it, he claimed to have slept with at least 1,000 women, and describes his experience engaging in a sixsome with some "nifty Canadian girls."