Is it unreasonable to see siblings separately?

[DBD1975]

If you have siblings do you sometimes see them separately or do you always include all of them in everything you do?

I am not talking about family gatherings where everyone is included, I am just talking about meeting up from time to time socially.

Either YABU not to include all siblings, or YANBU to sometimes meet up separately.

YANBU obviously! They are separate people.

I rarely see mine together

I think you should keep the invites out in the open and everyone should be welcome but accept that not everyone can turn up every time.