Eliminating an empire

[bizkitmaker13]

This is my first game, and the only player I've eliminated only had 2 sectors each with 1 planet left when I wiped them out. If I take out the 2 planets this race has remaining do i get the rest of the empire? Or will they relocate or do something to make me claim/take the rest of the systems?
https://steamcommunity.com/sharedfiles/filedetails/?id=1709297280

[wolkenwand]

If you take all of an empire planets the rest of the territory that you are not claimed will disappear! It will become wilderness again unless you claim it before you take them down, if you want to get all of this empire territory without claiming then declare subjugative wargoal, then merge them after they become your vassal.