To give consequences to daughter for waking the baby

No, I think that with three kids, they all have to take turns, and that you also need to think about the mothers welfare (both in itself and because she is usually the lynch pin of everyone else's welfare).
Did you read what I wrote initially? I'm just suggesting that the OP can tell her 7yr old not to come in and then positively reinforce it when she doesn't. I suggest that she explain the situation in a loving way and tell the kid off if she breaks the rule. Being compassionate doesn't mean just letting kids do what they want all the time.
I suspect we might be misunderstanding each other though as I'm thinking that you're saying that the mother should just let her seven year old repeatedly interrupt the babies 20 minute bedtime routine?

Bloody hell! Talk about an over-reaction! Terrible advice, the poor child is 7, she needs some attention from one or other parent while the other one is dealing with the baby. Sitting her down and reading her the riot act will make her feel confused and sad. She’s 7, not 17!

Why does it take two of you to settle the baby? One of you can settle the baby while the other parent does something with the older children or gets them ready for bed or whatever. I feel sorry for your DD. She’s only 7, she may be feeling anxious/left out due to the new baby and if she needs a parent, she needs to go into your room because for some reason you are both in there!

It would be horrible to punish her for this.

She is telling them that.

Because the 7 yo needs the mums attention
The baby needs the mums attention.

And she is being told very clearly that the baby's needs are more important. This isn't happening in isolation. This is the symptom of a child that feels like she isn't getting enough attention, all because if the baby, which is being reinforced by the mum going "baby needs me more than you"

Do this , it will most likely result in your 7 yo hating her sibling . Great advice .

That’s how children learn to grow up and be mentally healthy and resilient!? You don’t do it forever. You correct a bad behaviour in a positive way. She only gets the reward when she is being quiet and leaving the baby alone.

You think the third child should take priority over the other two? And that the other 2 should know that they are now second best?

Her behaviour is her telling her mum she's feeling left out.

Why would you punish someone for the way they feel?

My brother was 7 when i was born - he hated me! He used to put me in the big cupboard any chance he got and really, really played up apparently

Long term could it work out to not close the door fully when putting the baby down to sleep and allowing DD to come in as long as she is quiet? Have a chat about why he needs quiet to sleep. So she doesn't feel this time is off bounds and fascinating and the baby gets used to not needing total quiet? Maybe she can sit there and watch you settle him, feel included and hopefully will have less of a requirement to barge in.

I think try and figure out why she's acting like this, then look for workarounds rather than punish. Ultimately she didn't ask you to bring in another baby and has to adjust but you can't punish a 7 year old for not finding it easy.

She’s doing it on purpose. She’s 7 not 3! She’s well old enough to understand and she’s choosing to disobey, and then persisting when told not to (the repeated knocking).

I’d sit her down and make it quite clear her behaviour isn’t acceptable. I’d start by acknowledging that new babies are a lot of work at the beginning and it’s a big change for everyone in the family, but I’d also point out her behaviour is unkind to everyone and actually means that she’s getting less time with you because you’re having to re-settle baby and are tired.

If she’s forgetting then that’s different, of course, but this sounds like purposeful disobedience designed to cause you upset and trouble.

You dont need to give her consequences. You need to give her attention. She is craving positive contact with you.

What a ridiculous response.

I'll have to agree to disagree with you there.

Its a lot of years since mine were this age, but I understand the sleep deprivation, it’s a desperate feeling OP, so I can appreciate that you feel less than pleased with your 7 year old.
I think you need to determine if she is doing this for attention or is naturally a noisy child, I think she’s old enough for you to sit her down and explain that baby is very tiny and needs his/her special big sister to let him/her sleep.
Play a ‘quiet’ game with both your children… ‘let’s see who can tip toe the quietest up the stairs’ ‘who can close doors quietly’, ‘who can speak quietly’, etc etc, reward with a star chart, the most stars at the end of the week gets a treat.
It’s a difficult time and she might be feeling left out, new babies take every minute of our time, she’s going to want attention one way or another so she’ll be naughty if she’s not getting it for being good.
Praise and reward is the way forward.

That's what I'd do - positive reinforcement rather than negative consequences.

I would however have no qualms about having a proper conversation about her behaviour and say that if she doesn't stop doing it there will be consequences because you know she can do it it's that she won't or doesn't.

The baby also has to adjust to having noise around. Does the baby sleep if you have a radio on in the background? If not, you should practice and get the baby used to noise.

I agree with PPs that she likely is vying for your attention but that does not excuse her behaviour - she is crossing a boundary and you need to uphold that boundary kindly but very firmly. Her feelings are valid, using them to behave however she pleases is not.

Maybe something that's preemptive rather than consequential? An activity / programme she could watch while you put the baby down? A reward for her remaining downstairs successfully? A walk or outside game with the other adult?

"Let's make sure that the baby is FAAAST asleep, and then we can play!"

4 months is peak sleep regression! I'm not surprised OP is posting at this point down the line, newborns sleep through most things but 4 month olds throw it all out the window. Don't blame them for creeping around.

Mine is almost 6 and we also have a 4 month old. She is similarly disruptive at baby's nap time and i do feel there's an element of sabotage there, however subconscious. She'll do things like flick the lights on and off or decide to build noisy marble runs as well as bursting in to chat. It's hard but I personally try to see it through her eyes: that we are now constantly busy with baby and she feels shut out. I don't think she means to disturb the baby per se, but knows all our attention is in that room so she wants to muscle in too, having never had to wait much for our attention before.

My child is both articulate and artless enough to say things like "I want to be [baby]", "who's looking after me?" or, the doozy, " I actually wish [baby] hadn't been born 🙂". It's sad to hear but I'm honestly glad she feels she can say these things to me. At least I'm in no doubt as to her feelings and wants.

Your DD7 is probably struggling to orient herself in this new normal. I don't think punishing her will achieve much besides confirming her worst fears. But negotiating positive 1:1 time together - eg "if you let me get baby to sleep then you and I can [insert desirable activity] - is probably more constructive. This does mean you've absolutely got to stick to your word though. Just because she is old enough to amuse herself doesn't mean she should always be obliged to do that. She's allowed to need you too - and to struggle and sometimes fail at being the big kid.

This is v much a work in progress for me too. It's really hard. Sending solidarity.

Indeed, which is why I said that some definitely do!

No it doesn't. It says baby is top.

When they should all be equal.

Depends on the 7 year old

Explain the baby rule to both of them. Ask them for suggestions for consequences. Then stick to it.

Some definitely do 😂