How much schism does it take from the True Church before I become a Graceless heretic?
There are chruches in partial communion with each other (by relation)? I'm assuming they must still have Grace.
There are churches that don't maintain communion with each other, but then reconcile shortly after. These material schisms have even lasted for a century at a time in some cases, but later would retroactively confirm the orthodoxy of actions by the other in schism ( like confirming ecumenical councils).
There are then churches that are currently in full schism, yet hold similar beliefs, if not identical essential beliefs.
There are then churches that are in full schism, yet hold cultural differences in theology and may even debate the technicalities of an unknowable and/or unfathomable reality, but basic theology is essentially identical.
There are so many so willing to call the other an external to the Church, so tell me where. And if you cop-out with "I know where it is, but not where it's not", then you're no fun and just choke yourself.