If OP calls her ''step-mom'' it implies they're married. Though to be fair I have heard some people refer to their fathers girlfriends as ''step-mom''.

7, you can't become someone's step-parent without being married to that person's mother or father.

You can choose whether or not to have a step-father/step-daughter relationship with him and to actually thinking of him as your step-father but, legally, yeah, he'd be your step-father. Though, they don't have any actual legal rights.

I actually wasn't invited to my mums second wedding (even though we're very close)

Yes, they would be. You don't choose your step-parents unless you keep selectively destroying potential suitors before they can marry your parent.

It's really hard to form an opinion on this without knowing how old the OP is... It's a bad way to start for the step mom regardless of age but it's completely ridiculous if OP is 17, not QUITE as pathetic if OP is 10.

Either way, it seems a bad idea for a new stepparent to just start asserting authority without first having been around long enough to know what is or isn't okay according to the child's actual parent.

@17: I doubt a 10 year posts on FML but even if he did: No, it's absolutely never ever appropriate behaviour to boss around children that are not your own if you haven't known them for most of their lives. My parents divorced when I was 8 and every new partner they got was so out the window if they started treating me like they were my new mom/dad (in a negative way, and no I don't mean "can you please do the dishes"). Children do not like to be treated that way by a stranger, even if they're lived in the house for some time. You'll only grow resentment if you try to replace their other parent (situations like "no biodad in the picture, has known the child for their whole lives" excluded obviously).

No, that's a complete dick move to any adoptive parent. However, a reminder that she shouldn't expect to start enforcing a major home dynamic change on day one is needed.

An adoption is a process. One that would require the patent to meet the child At least once before its approved. Also just because someone marries a parent doesn't mean they automatically adopt said spouse's offspring.

4, it's a dick move on the step-parent's part to automatically assume that they get to actually be a parent to them - when they likely already have a mom to parent them - and can just ground them and all that right off the bat. It's basically like they're trying to replace OP's actual mom and that's not okay. OP should listen to their step-mom in regards to house rules and if she asks them to clean or take out the trash but the step-mom should not get grounding powers or authority like that until 1) they actually get to know and develop a relationship with the kid and 2) they talked about it in depth with their spouse and then the other biological parent of the child and 3) the child to see how they react and feel about it, if they're like maybe 15 or so. However, they should get no authority over the child if the child is no longer a minor.

"you're not my real mom!" *storms off angrily*

how long she's known the dad has nothing to do with how long she's known the kid. the op said she just met them yesterday, when they moved in.

Actually, it's not irrelevant. Inviting someone into your home when you have kids means that you as "parents" need to discuss how you will manage that. While I personally believe in managing children with their consent it is not necessary and not every home is a democracy. Also, OP is male.