Here (NZ) the generally accepted protocol is immediately after (a natural) birth that the baby is given to the mother for "skin on skin" time. Only broken briefly to weigh and examine baby.

The idea is to keep baby as close to mum as possible. Similar protocol for multiple births is to keep everyone as close as possible.

There's not enough data on if it helps, and co-bedding risks mixing up feeding, medications, treatments, etc.

The reason why people suspect it MIGHT help with multiple birth babies is that it might feel familiar to when they were inside.

https://www.cochrane.org/evidence/CD008313_co-bedding-preterm-twins-optimize-growth-and-brain-development

https://www.nhstaysidecdn.scot.nhs.uk/NHSTaysideWeb/idcplg?dDocName=PROD_353712&IdcService=GET_SECURE_FILE&noSaveAs=1&Rendition=web&RevisionSelectionMethod=LatestReleased

A sharpie to the forehead would solve the mixup issue.

There's not enough ability to research it. You're taking big risks that require getting permission from a separate family, with only a guess that it might do something useful.

There's not even much in the way of data as to why it worked in this case, or others. But afaik, it's only ever been tried in multiple births, and only ones that are in distress. That's why this was even tried; an effort to save a struggling preemie.

Not that research is impossible, but the barrier is a big one.