I am not certain you can "lock" any graphic to a position and expect it to move (increase or decrease in size) when you adjust the size of the main object. You can try to "group" the objects together but, I have found that process, when it works, may cause other problems within the drawing. Obviously, the best solution is to define the size of the map first...then add your other objects. Tedious I know...I worked with architecture drawings doing this same process.

However, other posters may have a better solution.