Answer
If the uncles trailed the aunts, then the magnitude of the force from the rod on the boxes would not change.
Also, the acceleration of the two boxes would not change.
Work Step by Step
In part (a), we found that the tension in the rod is $~~1.05~N$
In part (b), we found that $~~a = 3.62~m/s^2$
If the uncles trailed the aunts, then the magnitude of the force from the rod on the boxes would not change. This force on the box of aunts would still be $1.05~N$, but it would push the box of aunts down the slope instead of pulling. Also, the force from the rod would push on the box of uncles in the direction up the slope instead of pulling on the box of uncles in the direction up the slope.
The acceleration of the two boxes would not change.
