what is happening now, is the objects are moving on a path to the destination, when they overlap the objects are trying to push eachother out (using physics or solid) but at the same time they want to keep following the path, result is bad movement, so you need an extra behavior - ai
it is called "avoidance" but its something you should program yourself, there are not many or no examples of such behavior in construct, you can look it up on the web - rts avoidance, avoidance steering
what probably should happen if a collision is going to happen (invisible trigger), one object should decide to hold/stop the pathfinder movement until there is no collision, if you want the objects to keep moving, while there going to be a collision, then you need to steer/direct the object to a place where there is no collison
it will take alot of coding i think, but it can be done, but its pretty advanced