I used to work (20 years ago) in major donor fundraising, which included working with Royal Patronages. By major donors, at that time, it was someone who could give £10,000 without it being the slightest problem. Probably more now, given inflation.
The first thing you learn is the fiction of public relationships. If the donor mentions their mother is unwell, their child applying to such-and-such universities etc etc you record it. Next time you meet them you ask about it. People with that level of wealth expect that level of personalised care - they know you are not their friend, but they expect that sort of service. It looks very intimate - it's not.
That means you know if they have met your royal patron before ('we met at the XYZ charity polo cup in '99). So, when royal personage is doing the rounds at your event, you say to royal staff that you would like to introduce Mr and Mrs X, big supporters of the charity, who met Prince Y in '99 at the XYZ charity polo cup. The royal staff inform the royal personage and brief them quickly on the facts you have given them.
Prince Y and Mr and Mrs X, in front of the cameras, remember their meeting and are delighted to exchange reminiscences and say how wonderful the charity is.
Hello magazine print it up to imply that they have been BFFs since '99, bonded over their shared love of polo and their commitment to the work of the charity.
In reality, if they met in the street without an entourage they wouldn't recognise each other.
I am not pulling people down, I am being honest about these types of celebrity relationships. The true relationships happen in private.