How to avoid double intersection points.

Everybody,

I have a situation where i need a point at the intersection of a cycinder surface, with two datum planes witch are normal to each other.

This wil create two possible intersection points on the cylinder surface.

When I variate the cylinder diameter parameter, the intersection points sometimes switch from the left to the right & vica verca.

I noticed this because I had placed two datum points on the intersections (pnt1 & pnt2), and they switched position.

So my question: Is there a way to overconstrain this point ,or define a pos x-dim for this point, or define a quadrant for the location of this point,

so it always uses the intersection at the right side for example.

Ronald