Quick question--what is the actual current origin of the Stepford Cuckoos? I've never followed them super closely but I always assumed they were clones of Emma Frost, but is that not exactly true (like how Laura is technically considered Logan's "daughter" genetically now)?
They are living Sentinels like Fantomex, designation Weapon XIV.
When Emma Frost lay comatose after Trevor Fitzroy killed the Hellions. The Weapon Plus program harvested her ova and made genetically engineered clones of her. The 1000-in-One are able to link their telepathy in a hive mind in order to increase their magnitude of telepathic strength. Each one is a Telepath slightly lower in power than Emma, but as they link they grow stronger.
Five escaped Weapon Plus and became the Five-in-One and came to the Xavier Institute for Higher Learning (rebranded from the Xavier school for Gifted Youngsters) where Emma became their mentor.
After Sophie and Esme died they became the Three-in-one and once held the Phoenix Force inside diamond-formed hearts until Hope returned.
The Hive mind nature of them means that individuality can be hard for them as one of them tends to dominate the hive with their own personality.
They did go full individuals during Bendis's run but it seems after they decided they sort of prefer the hive concept, even trying to resurrect Sophie and Esme into other people before the protocols were revealed.
Since then they seem to accept that Emma is their mum. And during Bendis's run it was revealed that Emma can hive mind with them as well.