I don't know who the "friends" are, but the younger Yorks have such proximity to the disgraced Yorks that it's an unneeded risk to put them on the rota. Can you imagine if Fergie or Andrew wanted to come along on an appearance, unannounced? Fergie will do almost anything for attention and Andrew has been chomping at the bit to get back to royal duties.
Besides, do the princesses really want to put themselves and their families in the firing line for additional public scrutiny? They have more freedom and security right now than if they were touring about shaking hands and having tea with local dignitaries. I have no doubt they'd do an excellent job taking over many of the local duties, but there's nothing to suggest that they actually want to or have requested the opportunity. It appears to be the press trying to whip up a story.
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