OK, as a married man who has helped to organise the weddings of two daughters, and currently planning the third, i have learned one simple fact about weddings -
there will be grief - no choice.
The only choice you have is damage limitation - keeping the grief to a minimum - working out whom you can upset, and whom you can;t, and navigating your guest list accordingly, and riding out the storm.
That's fine for me, i am a private citizen.
Those luxuries do not apply to Prince William and his fiancee.
Their wedding is being financed directly, or indirectly, by the public purse, and as a nation, we have protocols to observe in the interests of interntaionl trade and diplomacy.
It;s the equivalent of inviting Auntie Marg because the couple don't really want her there, but the larger family do, so they will compromise and smile on the day.
I've done it, my children have done it, and I don' see why the royals can't do it.
If 'the couple' want only the guests of their choice - they should have a totally private ceremony which they pay for - as long as this is a public event, they have responsibilities over and above the notion of 'upstaging' on the day.