FamilyInstance.Location

Hi
I’m using the “FamilyInstance.Location” component to get the points of the family that is applied to the grid. The problem is that the points are shifted from the actual geometry in revit viewport. What I need is to have all points in the middle of each cell. How to fit them, or any other method to do it ?
And another question, how can I get perpendiculars to the cells ?
Thak you.