(there might be other evidence but it would help if you would explicitly point it out)

There's this, from chapter 80:

You would expect that chain of light to miss a step, sometime down through the centuries; that it would go astray at least once, and then never return. But it has not. The Line of Merlin continues, unbroken.

(Or so say those of Dumbledore's faction. Lord Malfoy would tell you otherwise. And in Asia they tell other tales entirely, which may not make Britain's version wrong.)