DD and car seat in grandparents car, WIBU to send my own car seat?

[LittleSweetpeaBell]

DD (2.4) goes to MILs one day a fortnight. MIL has a nephew who is a month older than DD, and MIL looks after him on a different day.

MIL has a seat in her car for both children to use. Unfortunately MIL struggles with adjusting the straps so has just left them so they fit the bigger child which is MILs DN, but he's quite a lot bigger than DD - DD is very small for her age, only just weighs 9kg (22lb) and is in 12-18 clothes, the DN is in 3-4 clothes and must weigh at least 30lb (13kg). So DD slides around in the seat and can get herself out of it. I consider it both mine and MILs responsibility to ensure the child is kept safe in the car.

I don't drive but have a seat I use in my DMs car which I could borrow to put in MILs car for the time she has DD. The seat is adjusted to fit DD perfectly and she can't get out of it. MIL has borrowed the seat before when her DNs childminder was ill and his mum needed to work so MIL had both children on the one day.

So WIBU to ask MIL to use our carseat and explain the reasons why? I know if she had an accident and DD was seriously hurt or worse she'd never forgive herself. Would you be offended if asked to use a specific seat for your grandchild?

Not sure how a seat facing backwards can affect hips? Its the same style harness and buckle as forward facing.

but with DD she can get out of it although she doesn't because she knows not to

But if there was a crash, it wouldn't matter if she 'knew not to' she wouldn't have any choice, she'd just come flying out the seat if the straps aren't right.

I also don't understand how the hip issue would make any difference rear facing. Lots of seats can be fitted forward or rear so she's sitting in the same seat.

If your MIL can’t adjust the straps I would be telling her she needs to get rid of the seat and stop using it for either child.

She's not a tiny baby, she's 2.4. I'm guessing that rear facing would be a problem because of leg room.

@Coconutpie the child is 2, just light. She’s probably too tall for a group 0 seat. ERF is a personal choice, and while safer, doesn’t work for everyone (works for us). They also can be fiddly to move between cars, and awkward in the back of cars with only 2 doors.

OP YANBU. Just say it politely and present it as fait accompli.

If she were rear facing tight straps would not be as crucial, because she would be forced backward onto the seat (if the car rolled over though tight straps become more important). However forward facing loose straps are very dangerous, they allow forward movement and then force sudden restriction in case of a crash.

@bonzo77 the OP says her DD is in 12-18 month clothes so sounds more like she is small as well as light. My DN is similar age and size and still fits safely in group 0 car seat so it is possible. My DC were also all small & light and fitted in group 0 after age 2.

I think a lot of people do take their DC out of group 0 before they need to (not saying OP has done this as her DD may be tall and very thin but most group 0 go to 13kg and at 9kg it is very possible she does fit in. OP also says her DD slides around in the bigger seat).

I've been told by her consultant for her hips that she cannot be rear facing as she needs to keep her legs straight when she's sat not crossed or folded like she would be in in rear facing. I have a letter from the consultant that I keep on me and give to whoeevers driving her around to say that she cannot be rear facing. when she sits normally on a chair she has to have room to stretch her legs forward as she gets pain in her hips if she doesn't.

She hasn't go taller or heavier in nearly 6 months this is also a concern and HV/Paediatrician are running tests, I changed her from the RF group 0 seat at 22 months old when the consultant told us to change her to a FF group 1 or 1/2 seat. She was needing to change when we moved her anyway as her head was almost at the top of the seat.

I'll have a chat with MIL next time she comes to pick DD up and just hope I don't offend her.

I think RF is safer and would have kept her RFing if it wasn't for her medical problems.

Next time say "MIL you've left the straps loose on DD. They must be tightened in case in case there's a crash/car rolls upside down. It can happen even to stationary cars. I know it's a pain but it would be awful if the worst happened."

Don't accept any excuses i.e. not going far or fast, too tricky etc. Tbh I'd be rethinking leaving my DC with someone this dense.

A small 2 year old would have room for straight legs in most rf seats. It's only as they get bigger they have to bend/cross their legs. I would say it's easier to keep legs straight as they get bigger in rf too as they can rest legs against back. In ff, their legs tend to hang bent over the seat. Not a criticism of you, OP as you're just following what the consultant said.

If MIL is offended by you wanting to keep your DD safe in the car, I don't think I would want her looking after my DC anyway. If your MIL said she wasn't going to hold your DDs hand crossing the road or leave her next to a fire unsupervised, you wouldn't trust her to look after her. Same with the car seat, if she can't strap her in properly she is not responsible enough to look after her.

Can we just stop telling the op which seat to use and help her to help her MIL keep her DD safe in the seat she’s currently got available?

Where my childrens' safety is concerned, I don't give a damn who might get offended if I insist on things being done correctly.

I'm shocked you've allowed your child to travel in a car seat that's not safe for her, and all for the most irrelevant reasons - not offending your MIL. Just present it as a done deal; no questions, no wiggle room; as though of course MIL wants her grandchild to be safe.