Is this an unusual family set up?

[NotinaboxNotwithafox]

Maybe this is how it is for others too. My dad has been married to my stepmum 20 years. They married once all children were adults. She has 2 children we met at their wedding but we never spend time together.

Is my question confusing?

What happens at Xmas/other “family events”?

So you don’t spend any time with step siblings you met 20 years ago as adults?

Seems normal to me. I’d expect to probably see them at christenings, weddings and funerals.

That’s how often my DH sees his actual siblings for the most part lol.

I suppose you haven't had a chance to form a bond with each other as you didn't grow up together so not unusual.
However, if it were my children (adults or not), I'd encourage friendship based on step-familial ties, and family get-togethers.

I guess I’d have expected that you would have met each other since, either at a family get together of some sort or just coincidentally being in the same place eg visiting your dad and step mum at the same time. For this to have never happened makes it seem like something one party has actively avoided unless there are real reasons such as geography, immobility etc.

DM has been with her partner for 15 years (DDad died 25 years ago). He has 2 adult daughters. I have never met them. They see their mum or in laws at Christmas; I sometimes stay home or see my PIL at Christmas. We all live in different parts of the country.

We met once as children/teens and once as adults so yes understandable there isn't a bond. We're strangers. They sound nice and I would have liked to have gotten to know them a little. Geography is definitely part of it.
Sounds like it's fairly normal.