It is my understanding that the expansion is not due to a 'force'. It just is space expanding. If it were a force, then those galaxies, way out there, would be subject to F=ma and general relativity constraints. If the force is so weak, then far away galaxies would be limited on their velocity.

The planets are in stable orbits with respect to one another. So if Earth's orbit moved slightly with respect to the other planets, gravity would nudge Earth into a stable orbit. Likewise for the other planets. They would all 'dance' around until stability was achieved.

If the planetary orbits are indeed moving out, then it must be imperceptibly slowly. One of the astronomers out there could probably estimate the rate of orbit expansions.