Husband thinks it’s ok to let children change baby’s nappy

Who is the 4yo in relation to the baby?

I'm sorry OP but I think YABU. While yes a baby's parts are private they are not private in the way of an older child simply because they need nappies changed. In a nursery multiple people may do this. It's normal for extended family to change the occasional nappy too (if people are lucky enough to have help). It's good that a 4 yr old is helping as long as the baby is secured safely and the older child is supervised in terms of hygiene.

I used to changed family members (babies) nappies as a child. There was absolutely nothing sinister about it. I loved feeding, bathing and getting my niece dressed. We had a lovely bond growing up. I would have been around 4 YO when she was born.

However; as an adult I remember insisting on moving to another room when MIL said to change my DCs nappy in a room full of adults one Christmas. DC was just over one years old. Adults were all family but I didn't want my child exposed Infront of a everybody.

I wouldn't like it either ...something about the touching of an intimate area that should be for a responsible person and not someone no matter how adorable might get things wrong or explore or begin to think mutual intimate touching of any sort is ok between relatives and it be a gateway to unwanted touching.

I hear you OP. I also experienced SA as a child. I don’t think children should be encouraged to touch another child’s genitals under any circumstances.

If these children are his children they are your child’s siblings, not random children

This must really difficult for you and im not sure if there is right answer. From my perspective my elder daughter does help my 2 year old with nappy changes. I think she is learning to help within the family and become a good care giver when she is older.

You are overthinking this. Getting a 4 year old to help is involving them and ensuring they don’t feel left out. I suggest you talk to someone about your past as it’s clouding your judgement now.

If his child is a close relative, helping with the baby is a way of making them feel included and part of the baby’s upbringing before they can actually interact properly or play.

If they’re siblings they will see each other’s private parts thousands of times and it’s really not comparable to reinforcing boundaries around others touching your private areas inappropriately!

My two kids bathe together every day (opposite sexes) and my DD is obsessed with babies and putting nappies on all her toys and would absolutely love to be included in that way with any future children.

'She likes it'? As in the child or the baby?

I don't think the barrier cream is appropriate whoever the other little girl is.

Yanbu, my older child helped but that was just passing me stuff. Not the actual changing, they wouldn’t have done it properly at 4 but also yea I wouldn’t be happy with that

Adults take care of babies, not children.

I’d be happy for an old sibling or cousin to “help” (bring things, entertain the baby during etc) and to observe but 4 yo is far too young to be changing nappies.

Your baby isn’t a doll to be played with. Whether the 4yo “likes it” is less important than whether it’s a good thing for the baby.

The baby needs a competent care giver changing their nappy, not a very young child.

Would you feel differently if the 4yr old is your daughter too?
Is your partner aware you were abused as a child?

Please have a conversation as all this is deeply rooted and as you navigate motherhood all historical events can be brought to the surface.
Congratulations on your DD

Is the 4 year old a step daughter?

Why are there random children in your house? Or is this 4 year old a sibling to the baby?

Is the 4 year old a stranger? A sibling? A friend's kid? Your post isn't clear.