Is this bonkers SIL behaviour or am I overthinking it?

It sounds a lot like post natal anxiety and she deserves some empathy that is seriously lacking in some posts on here.

She sounds extremely anxious. Not nuts.

And you sound really unkind to a new mum who is clearly struggling to leave her baby.

Might feel a bit ott however if it makes her feel more comfortable and able to leave the baby then just go with it. Send regular updates too, even if you feel it’s too frequent. My mil had 3 kids and 3 other grandkids however wanted to front face in her car seat, bed with a duvet and pillow, rice in bottle with her milk etc so was important I was clear on how I done things and that this was respected before she babysat for us. It’s nerve wracking leaving your baby the first time.

Of all the anxieties to have, rhis is weird

Tell her to poke it! She sounds overly controlling

very soft YABU.
yes, it's a bit much, but she's clearly anxious about leaving the baby.
it's just a small thing that will reassure her. and I don't think it means you don't know what you're doing. just that she's worried about something going wrong when she's not there. I'm sure that in time she'll become more relaxed about it.

Make sure you remind her...

As a first time mom, I guess that's understandable, however weird it may sound. Also, it's better than delegating the baby to you every chance she gets.

She sounds super anxious. I think, just show her some kindness and empathy, show her what she wants, speak to her about her fears and just relay to her that baby will be safe and loved.

To be that controlling she deserves to be tied to home and baby. If it was something abnormal or medical I get it but you actually have more experience than her!

The funny thing is ime that dc don't stick to the same routine as at home anyway.. Dgc slept through from 5 months at our home. Never did anywhere else.. Not even at home. Just used the same schedule as similar age dc I had.. Worked a charm it seemed. Dil was fuming!! Half arsed laughed anyway!

Oh wow. Defo weird behaviour. I wonder if she’s going through post natal depression. I recall being worried about people picking up my daughter and dropping her despite them having children. Looking back and the fact there were other flags I think I was suffering post natal depression but didn’t realise

Ha ha ha. Well said

There's nothing wrong with lifting the baby's legs up by the ankles to change them. Some rumour has been spread by certain HVs that it affects their hips but on a healthy baby, no it doesn't.

The bottle thing is relevant - the guidance for how to feed babies to avoid wind has changed since I had last bottle-fed a baby, and paced bottle feeding is important to those of us who endured painful weeks of triple feeding before getting breastfeeding sorted.

Humour her! She wants a night out and can’t manage it without over-checking.

Worst bit… She was a nursery nurse. I learned after that never to let any of them have my children until they could speak. I was told by several members of their family that I was unreasonable, which is why I’m not going to judge this new mum. OP might have three kids that dragged themselves up (not suggesting you do OP) so I won’t invalidate a mothers instinct.

This^

I had horrible anxiety about leaving ds for a long time after he was born. People would kindly offer and I tried a few times and it was not pleasant for me in any way so it really wasn't the help people thought it was. It was absolutely nothing to do with me not trusting them - logically these were people who I knew and cared about who I knew would be good to ds and look after him. I just couldn't shake the feeling that something bad would happen and I wouldn't be there for it.

It may just be that she's struggling with anxiety and needs to prove to herself that baby will be OK so she can feel OK about leaving him - all about her and her own mind not actually anything to do with you.

I would also just say that not everyone who has children do things the same/ right way. When ds was little the first nappy my sister did (2 lovely kid's of her own) I had to redo it because he still had poo on him. When he went to nursery and I gave them a bottle of breastmilk for him they added water to it like you would with formula. People make mistakes and things happen. She's a new mum and she's trying to figure out what to let slide and what is worth worrying about. Not everyone adjusts seamlessly into parenthood.

@WhimsicalGubbins76 🙄🙄🙄

1. 8 months old is a toddler

1. I had both pre & post natal anxiety so bad it was nearing psychosis!

The absolute worst thing you can do, is enable it and condone it! The only way I managed to recover was to see it, recognise it and face it head on.
I had to live with my mum for 3 months when my DD was 8 months old and if she'd have gone along with my ott madness, I would never have recovered! It would’ve escalated & escalated and my mental health would’ve worsened & worsened. It’s common sense.
I'm not suggesting OP stomps off laughing or tutting! You can still be compassionate, empathetic and kind without doing the role play!

I'm entitled to my opinion

I'd say something like "oh I've never been keen on tests, see if someone else wants to be graded by you" and let her search high and low. You're doing HER a favour by babysitting her child, not the other way round

The nappy is a bit weird but the feeding I get, i have a very sicky baby and after having tongue tie she is at risk of still choking on milk if she gulps it too quick. We pace feed as well. MIL's technique was very different to what we'd been doing so we were glad we observed and she was happy to adjust to what we'd like her to do for baby's safety.

^ This.

Unless she is normally a nightmare I would put this down to PFB/anxiety behaviour.

I cringe when I think of the instructions I wrote out for my Mum to look after my son (2 sides of A4 if I remember correctly) when I left him with her. Right down to which direction to rub his back 😆. She just went with it and humoured me! It's almost certainly about her and not you or she wouldn't be leaving the baby with you at all. He's 16 now and although I'm still neurotic I know it's me not anyone else.

Agree with PP definitely PFB. I remember the first time I left DD1 with my mum for an hour and I phoned 5 times whilst I was out. I wouldn't take it personally.

I think the OP offered to help through kindness and was a little taken aback by the rather unusual response.

I find it very unusual anyway. I've babysat a lot of different babies and kids over the years and not once have I been tested beforehand.

Don't be mean, she's probably anxious. Don't offer to help if you're going to butch behind her back.