Is a/the scion always the successor of the current family head?

Question

Nothing I found online regarding the word seem to indicate that a noble family can only have one scion, but in media I always see the word as being singular and most important, usually regarded as the successor of the current head of the family. But is it always the case?

Can any child of the family be called a scion? If I say, 'X, a scion of the Y family', can you assume that X is the successor of the Y family, or should you think of them as just a child with direct lineage to the Y family such that they're at least on the order of succession?

Answer 1

The original meaning of scion was a shoot of a plant, as used for grafting onto another plant. Hence, any offspring of a family. If you have looked at online dictionaries, you will have seen that some, such as Merriam-Webster, give the additional definition 'heir of a family'.