# Merger of old black holes

On the eve of a possible announcement on the production of gravitational waves via a black hole merger, I think this question is quite aptly timed. I have a few questions regarding the evolution of the entanglement entropy of black holes

How does the merger of a black hole affect the entanglement entropy of Hawking radiation? Changing the shape of a black hole via deformations usually changes (atleast) the subleading order corrections to the Bekenstein-Hawking entropy and the entanglement entropy. Let us consider the merger of two old black holes (i.e. $t_{BH} > t_{Page}$) which (according to some controversial thought experiments) have no interiors which is accessible to an infalling observer. Does the merged black hole solution still admit no interior which is accessible by an infalling observer? Or in a more concrete physical picture, does the thermofield double of the resulting black hole still diverge?