To ask you at what point do you become a step parent or step sibling?

[PerverseConverse]

I know a few people who firmly believe that in order to be a step mum or dad then you must be married to your new partner. Others believe that living together or just being in a relationship together automatically makes you a step parent to your partner's children.
I grew up in a family where there were no 'steps' so don't have personal experience of this hence asking opinions. My mum gets really confused by this and usually argues that step is only if married but then if the couple have children together and have existing children on each side then does that automatically make them step?
I hope that makes sense. I promised her I'd try to find out but am probably not explaining well

Well some people talk about their MIl when they aren't married, but the term still actually means the mother of your spouse.

I started thinking of my mum’s partner as my stepdad after he’d been in my life about five years because my teenage logic had decided he wasn’t going anywhere and stepdad was less of a mouthful to say

It would depend who I were talking to. Officially I would say upon marriage, but if it were a stranger/acquaintance I'd probably say step mum. In the same way as I would refer to my DP's sister as SIL if she came up in conversation to someone who didn't know her as it would be quicker!

Officially it's on marriage - that's what it means. I agree people will use it informally in much the same way as MIL - it's a shorthand. "My girlfriend's kids" or "Mum's boyfriend" works just as well though.

If a couple with children each have new children together, then the new baby doesn't have step siblings, the existing children are their half siblings as they share one parent. Step siblings aren't related by blood.

Officially, or technically, your Mum is right - the term is for when you are married. However a lot of people just use it as shorthad, as pp said, same a MiL or whatever.

I would say marriage otherwise surely it's your Dad's girlfriend/ boyfriends kids?

I agree with your mum.

People who refer to their Mil etc when not married make me twitch - they’re literally not that at all, if you’re unmarried.

Step-siblings is different to half-siblings

I would say you become step sibling if your parent marries the other child's parent, but I appreciate that if the couple have lived together as a couple for many years then children are likely to refer to their step-brother/sister even if there is no marriage

To me a step parent is at the point when the adult assumes some kind of parental relationship to the child, marriage being fairly irrelevant. If the child is already an adult then they may well never assume a parental role so the relationship more likely to be 'Dad's wife' rather than 'Step mother'

If you share your Mum or Dad with another child but not both parents then they are your half brother/sister regardless of whether marriage is involved

Op if they have children together they are siblings, half not step. Step siblings would be no blood relation eg if the woman or man who isn't the biological aren't and children of their own from another relationship. I find the term step very offensive in the situation where ex and new apartment have children, they are blood relations.
Honestly beyond that for the ex's partner who cares what label is used - if children preference is Stepmom as that's how they feel then fine. In most homes people are referred to by name if not the biological parent. Eg their first name

My phones autocorrect is mental ! Sorry for the lack of English

Technically when you're married. But I refer to DP's DD as my DSD - it's just easier to say that tbh even though we're not married yet.

I have been with DP for 7 years, and he has a son. We have joint finances that pay for his university and have been through the pain of GCSEs and A-Levels together. I don't care that we aren't married, he is my step son. And to imply that a piece of paper would change that relationship or make it any more 'real' is frankly ridiculous...

only when married imo.

When you're married or have adopted them, I'd be a bit peeved if my ex new gf called our children her step children.

I think I became step mother when DP's DC accepted having me around being normal. I would shudder to say they are my boyfriend's DCs. My DP's DC are grown adults with children as are my DCs. I imagine the cut off age for boy/girl friend to be about 25 or 30 at the latest.
We are not married but to me the acceptance into their family was when I became step mother. I am referred to by my name.
I think that the Step mother/father/daughter/son title is the legal status after marriage.

Officially it's once you're married. If you're chavvy like my cousin it's after about three dates with a bloke.

Holey, if you’ve adopted them they are not your step children they’re your children.

I use it as shorthand because it’s quicker than my-boyfriend’s-son, BUT I never do it in front of him and when it comes to things like (they’ve doing recently) looking at schools because I’m not his step mum so it isn’t my place. I do understand why people hate this. I would have done with my dad’s revolving door of girlfriends. My boyfriend uses it as shorthand too, because I parent and look after his son. I think as shorthand it is okay and actually before marriage of course you are a step parenting. But when you use it in front of (young) children or children who haven’t talked to you about it, it has to be post marriage.

I always think there's an air of desperation about labelling yourself as a step parent to young children before marriage. You seldom hear actual parents doing it with a partner's kids.

I have never called my DP's adult children my step children as they have a perfectly nice mother of their own. But my DC refer to them as step brothers which is lovely as it shows there is a bond and they all get on really well.

@trippingthevelvet In what I honestly mean as a non combative way, what’s you’re take on people who have been together for years and years who have raised children but never married?

And to imply that a piece of paper would change that relationship or make it any more 'real' is frankly ridiculous...

Not 'more real'. It's just that certain relationships are blood, some are convention, and some are legal. It's not a 'piece of paper'. It's a contract. It's not nothing. You can't be a MIL without any law.

Surely it depends on how the child sees it

Honestly - only after marriage. To me that is what step parent means. If the couple have children together those “new” children are half siblings to the existing children but the existing children in each side would imo only be step siblings to each other if the couple marry.

Those I know in “blended” families only used “step” whatever after the wedding. Up until that point it was “mum’s partner”, “my partner’s kids”, “[new partner’s name]’s kids etc,

Thanks everyone for your thoughts. I know of someone who tells people her partner's kids from his previous relationship are hers too and I don't think that's right. They don't live with her but visit regularly. She refers to herself as step mum. It's a bit odd. I lean towards the "when married" too but then if people have been together for years I see where they are coming from with the step thing. I guess if they then split up any step relationship would not longer stand.