DC is 15 months old.
I'll try and keep this as brief and neutral as possible.
Parent 1 does not want DC to be left with parent 2's sister and partner mostly because they don't agree with their parenting style regarding things such as discipline. Although there has never been cause for concern with their DC, neither have done anything wrong but wants their sister to be able to look after DC.
Parent 2 agrees that they have different parenting styles from their sister and partner but is willing to let both sisters look after DC if they ask, but if there's anything that raises concern to stop any outings. Parent 2 has said if Parent 1 is not willing to let their sister look after DC then they will support this, although they disagree but will not allow either sister to look after DC.
Who is bu here?