To not want MIL to “redo” our baby’s name with her priest?

Because they have knowledge of Catholic customs, and those customs mean something to them, and they understand them better than a non-Catholic would?

I would need a practising Jew/Muslim/whatever to explain their rites and culture too.

(And just to piss on your chips a bit more, I was raised bidenominational CoE and Catholic, until I objected to Confession - at five years old I was rather insistent that I hadn't sinned - and my parents respected that. So I bring the perspective of someone with largely agnostic parents who engaged in CoE and Catholic rites for social reasons.)

Quite right, TheignT, and I am blaming those who take this attitude rather than the church itself on this one - though equally there's no denying that plenty in its hierarchy feel the same way and are very keen to encourage the idea that theirs is the best and most correct way

In actual fact its merely an option among many others, but then that's coming from someone who detests religious coercion no matter where it's coming from

The MIL is outrageous but it's a bit bizarre that she is the one who is religious and yet you guys went for a CoE baptism?

Well what Rome says is this child has been Baptised into the Christian faith, totally valid in the Catholic church and not only does she not need to be rebaptised but rebaptism isn't recognised in the Catholic church.

Blame the MIL not the Catholic church.

it keeps being said but grandparents do not have the right to be involved in decisions about their grandchildren unless the law says so. The parents discussed the situation, including the request from the Op's parents and agreed what they would do. They did tell the Mil, she was at the C of E christening and smiling. Its conceivable that if the Mil had ASKED the parents if they would go to her church for the priest to bless....just bless....the baby, they might have agreed. She didn't do this. instead she misled her priest and kept her plan a secret from the parents.
I see no mitigation for the Mil's behaviour. From what the OP has said, she didn't storm round to the Mil's house and tear her a new one, she was polite to Fr Liam. This is not an "equal shares" situation. A baby is not something that grandparents can expect equal to access or say in how they are raised. Hopefully this will now mean that the Mil will understand and accept this because she will be the loser if she doesn't.

If the MIL felt so strongly about this then she should have said something when her son married a non-Catholic woman

She very probably did, but once again she doesn't get to impose her own choices on others, and if her DS opted to marry "outside of the faith" then that was a matter for him

It's coming out very strongly on here that some (and that is only some) catholics expect their faith to be regarded as "primary", and they'd do well to realise that they don't get to dictate that, no matter what Rome might say

She didn't need to speak to the MIL beforehand at all or to get her approval.

It's nothing to do with the MIL what religion the baby is baptised in. The parents decided what they wanted to do between them and then went and did that which is their right. Also it's highly unusual for a non-Catholic mother to baptise their child Catholic so if the MIL felt so strongly about this then she should have said something when her son married a non-Catholic woman.

He has. Per the most recent post from the OP "DH spoke to her earlier and told her (very firmly) that it’s not happening and that she’s massively overstepped."

Your MIL was being bat shit and deceived her priest but you had your DC christened according to your DPs faith but not hers, even though hers means more to her, while claiming neither of you have any.

Totally fair enough if you personally are actually a bit CoE whereas your DH is not catholic at all. Or you have issue with the Catholic church that you dont with CoE. But whatever the reason why you should have spoken to MIL beforehand about your choice for the christening beforehand and could have given her the option of a blessing then on your terms.

Even if the bit about this suiting OP's family but not MIL's, and even if it had been done deliberately, why exactly should that be changed?

Like everyone else MIL's absolutely entitled to her choice of religion but she doesn't get to impose it on others, and though she almost certainly believes otherwise hers isn't the "superior/premier" one in any way

Of course that leaves the option of indulging her to be "nice" and "inclusive", but given the way she's behaved I'm not sure that would be wise

…and just to add, a Priest will bless any child that is carried up during Communion.

I certainly don't get the impression from the OP's tone that she would have gone in all guns blazing and kicked up a stink. She sounds very measured and sensible to me and filled the priest in on details MIL had omitted.

My mil is a bit like this and wanted us to have a 'proper christening' ( church) as she honestly believed that a baby who may die without being baptised would never go to heaven and be in purgatory for ever. She adores her grandchildren and was a ball of stress about it so I gave in and had their christening in a church even though my dh and I aren't practising. She's otherwise lovely and it was coming from a place of love so I did it to save her from that stress.
Id want them to use their proper name though.

I suspect that she wanted to know what MIL told him and what this event was because MIL sounds very vague and evasive-

Well that's the thing isn't it?

If it wasn't another Baptism wouldn't Fr Liam have said?

If it was a simple blessing & acknowledgement during mass, what's the big deal about the name?

No evidence that she kicked up a stink. Considering her balanced tone on here, I suspect that she wanted to know what MIL told him and what this event was because MIL sounds very vague and evasive- imagine not discussing this with the parents beforehand?

Very bizarre. Everything about it. Your husband needs to put his foot down!

Our local Catholic is so under subscribed they happily accept heathens. So not sure its as useful as it sounds.

Actually that's true in many Anglican churches, not sure if all. There have to be the three requirements, same as baptism by a priest or vicar. As previously mentioned, these are use of water, invocation of the Trinity, and intention.

She’s not ‘in the congregation’ though. And I think the priest who performs the services probably knows better than you, no?

It’s not happening. Read the update

I would go along with it - never know if you might want to send your child to a catholic school.

Any Catholic can baptise a baby into the Catholic Church - It’s normally someone Ordained, but they don’t have to be.

Well the MIL, and presumably other members of her family, saw the child being Baptised, a valid Baptism accepted by the Catholic church. No need for anything else.

I don't think that is a fair way to describe this. If, for example, you are at Mass and have a child who can't take Communion the priest will bless them if you take them up to the altar. This doesn't need to be prearranged, the priest doesn't need to use the child's name so no what this grandmother has "arranged" isn't the default.

I don't know much about the catholic faith, but the MIL is not a good ambassador!!!