The formula for the force of gravity has ( M₁ · M₂ / D² ) in it.
After the changes, the new force will have ( 0.5M₁ · 0.5M₂ / (0.5D)² ) .
We can separate the new numbers from the original force, like this:
( 0.5M₁ · 0.5M₂ / (0.5D)² )
= ( 0.5 · 0.5 / (0.5)² ) times ( M₁ · M₂ / D² )
The first factor boils down to ' 1 '. So, those changes would
leave the strength of the force unchanged.
That's what I think.