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

It's not a 'piece of paper'. It's a contract. It's not nothing. You can't be a MIL without any law.

True, but I was talking about my Step Son - not my step son in law!

I've got a MIL despite not being married. I have the best stepdad in the world despite him not being married to my mum, and my son calls him granddad.

Can only feel sorry for people whose relationships to each other depend on legal recognition.

After you marry.

I thought of myself as a stepdad when my SD asked me if it was ok to call me that because she wanted to. I feel much better for letting her choose than for forcing it upon her because of a legal ceremony with her mum.

We have never pushed faster than her or her sister indicated they were ready for. I think it would upset the eldest especially if she was told I should be referred to as 'mummy's boyfriend'

After you marry.

Also you can’t have In Laws if you aren’t married. It’s in the name. Treat them as such no problem but they are not technically your In Laws unless married.

I don’t think you have to be married but at the very least you have to be living together and entirely committed to being together. Anything more casual, imo, and you aren’t a step parent.

Morriszap why don’t you just view your “mil” as your partner’s mother? Do you call your dp your husband (or wife) even though he isn’t?

Yes, I often do say husband in non personal contexts because trades people etc understand it without explanation.

Obviously anyone who knows me, knows we're not married. Mil is easy, quickly understood shorthand.