Placement of Families withen Scope Boxes

[William Troeak]

When placeing a wall based family on a wall that is located withen a scope box I have the tendecy to place the Family on the wrong level.
It seems that the levels outside of the scope box which are offset by about 15"
are options for placement.
How do I make the family reconize that it is to be placed based on a level withen the scope box only?

Thanks in advance....