How to edit the corner post of railing just like wall?

[Sleepingfish_Kuo]

Regardless of the size of the corner post, the auto snap point is located at the center of the corner post.
I want it can be adjusted to use the edges of corner post as the reference for snapping instead.

[RDAOU]

@Sleepingfish_Kuo 

Reference or snapping for what? 

the balusters are nested components which are driven by the rail and not driving it. If you wish the end of the rail to be at the end/edge of the post rather than it’s center, then you would need to adjust the offsets of the balusters.