Orbital Disturbance - Placing New Structures

[karakris]

Riiight - Two Questions regarding the CONSEQUENCES of Adding New Massive Structures to a Stable System.

ONE - Kemplerer Rosettes.
In Theory these can exist - but take a Sci Fi Situation.

An Advanced Civilisation has created a Kemplerer Rosette of Six Earth-like Planets - in a circular ring.
This orbits around a central Sun / Star - at the correct Orbit for Habitability.
Now - I KNOW this will not be Stable, it will get out of orbit around the Star, and Planets will hit the Star.
However - A Civilisation clever enough to do this, can put in corrective measures to keep the Planets all orbiitting at the same Radius, and correct any perturbations.

What I want to know is this - Will these Planets actually HAVE Lagrange ( Trojan ) Points ??
If so - would it be possible to put some large Artificial Structures into orbit ( around the Star )in the Leading and Trailing Lagrange Points ??

TWO - Another Planet

Simply this - IF an Artificially constructed Planet with the same Mass as Earth, was put into Orbit around the Sun - exactly opposite to Earth.  Assuming that means can be provided to keep it in Orbit and exactly opposite.

How would this effect the rest of the Solar System ?? Would it have dire consequences, or not ??

[vh]

i don't know about 2 but as for 1 i would say probably not and if it were not for all the satellites and spacecraft we have in orbit we would probably not even know about the second earth -- try it out for yourself in universe sandbox