The main difference between the BRF and certainly the Continental royals is that the Continental royals socialize among themselves as families. While the BRF socialize individually on a one to one basis with whomever they happen to be personal friends with.
Even if the various Continental countries are not that close, these family gatherings mean that the monarchs, the heirs and to a considerable extent the spares have plenty of opportunities to form bonds, which would otherwise not be that natural, should they have to wait for an official opportunity to meet.
Example: M&F have personal relations with the royal families of Spain and Monaco, even though these countries are not as close to Denmark as say a more neighboring country like the Netherlands.
Such relations stems very much from having met in an informal, festive setting, where they have been dancing, cracking jokes, talked children and been sitting in a lounge with the ties loosened, with a drink, chatting away and fixing the world situation - just like the rest of us do, when we are at parties.
It takes a lot longer, if it happens at all, to start personal friendships if you only meet occasionally at official events, where there are schedules to adhere to.
The only exception from the BRF are the Wessex.
The Continental royals hardly know William and Kate, or Harry and Meghan or for that matter Andrew, on a personal level. Because they rarely meet at anything but the occasional lunch or dinner in connection with an official event.
And now the Continental heirs are taking over. They know each other well, having met informally numerous times, but they don't know W&K, H&M or for that matter Charles and Camilla.
It's not my impression that W&K and M&H have formed bonds with their Continental colleagues of their generation, i.e. 30-55 year olds.
Okay, the Continental royals show up for jubilees and other major events in connection with the BRF. - Of course they show up, when they are invited.
However, I can't help picturing an image of say QMII standing with Queen Maxima and Queen Letizia in a corner at the reception afterwards, asking Letizia: "How is your youngest then? Still shy?" And Letizia answering: "Oh, she's having her first crush! On a singer in a boy band." With both Q. Maxima and QMII exclaiming: "How sweet!" - Because they know each other informally across the generations, having met on numerous occasions. And as a natural consequence when they meet, they catch up.
I fear that apart from Sophie of Wessex any other member of the BRF (perhaps apart from QEII herself) standing in that group would desperately go through the mental encyclopedia: Letizia's youngest, whas'her'name?
Also, the Continental royals visit QEII, and sometimes Charles and Camilla as well, when they happen to be in London unofficially. Of course they do that's common courtesy. It's after all QEII's turf they are on. - But as I understand it, it's a cup of tea or two, but hardly a sleepover where they are burning midnight oil catching up on the latest gossip. As we sometimes see with certainly the younger Continental royals, even if some of them have now become Regent Couples.
Perhaps that will change? I can easily imagine H&M, both being extrovert and newly married join and being welcomed within the Continental royal social circle. Without leaving the Wessex out of it. Why should they be left out?
W&K are (my impression) more introvert personally and they also start at an disadvantage, should they decide to join the social circle.
Let me explain: Continental heirs and spares join the royal social circle when they come of age, if not before. When they marry, their spouses are introduced into that circle shortly after. Neither William nor Kate have had that introduction, hence why they would IMO be at an disadvantage.
If ten years pass before Harry and Meghan join the social circle, (someone are bound to replace the Wessex eventually anyway) they will be at an disadvantage too.
It's akin to a street, where each house represents a monarchy and a royal family.
These families visit each other from time to time, complete with a dinner with white tablecloth and the best china on the table.
But apart from that most neighbors host regular BBQs in the back yard as well, where all are invited and most show up. - Except for one family, where usually only one of the sons and his wife show up.
And when that one family have a BBQ, they only invite selected members of the other families.
If you lived on that street, how would your personal relation with that one family be, compared to the other families?
- So if one of the younger sons of that family and his wife decides to join in, it will inevitably take a little more effort for them to become a part of this circle of neighborhood friends.