Recently scientists observing 2 black holes apparently noticed that after the 2 had merged the 2 together had lost mass to the equivalent of 3 solar suns. The standard theory of gravity has no answer to this mystery, however if you believe as in New Gravity that every individual particle of any mass pulls the space itself towards the mass and is not attracted to any other mass whatsoever. If you also realise that black holes are not physical entities at all but manifestations and indications of streams of space passing through that area or areas. The 2 black holes involved start in different galaxies with their own gravitational percentage concomitant with their placement in each galaxy. Once the 2 are merged in one place a great deal of the gravitational pull that used to pass through them or affect the new black hole simply passes them by, not close enough to show the effects but still remaining in existence. Nothing is lost but, 3 solar masses no longer contribute to the merged black hole.
It is important to eliminate the idea that masses are attracted to each other, many problems are created such as spooky action at a distance. New Gravity is the way of progress.