Why the widget detail matters
With twins the expensive mistake is not forgetting to log, it is logging against the wrong baby and then having to unpick two timelines to find it. Each widget carries its own baby, so the button you press is the baby you meant. Inside the app the same thing is true of the quick-log panel: it logs for whoever is on screen, and the switch between them is one tap at the top.
Two babies, two sets of patterns
Nothing is averaged across them. Each twin gets her own night score, her own weekly digest, her own sleep and feed charts, and her own nap forecast computed from her own last fourteen days — which matters, because twins famously refuse to be on the same schedule. Growth is per baby too, with a full chart for each of them.
Both parents, one log
Twins usually mean two adults on shift. A six-character invite code puts both of you on the same records, each entry carries the initial of whoever logged it, and everyone's widgets update within seconds — see sharing with a partner. One subscription covers the family, not per baby and not per phone.