can you make a point coincident to a chain of lines/arcs?

Here is a simple example. I've got a construction line that is coincident and tangent to a line. That line is tangent to an arc. (ignore the stuff in the lower left corner, that's not the active sketch). 

For different configurations, the point of that line changes, based on a dimension from something else. But sometimes that dimension pushes the point onto the arc. Well, it Doesn't push it onto the arc, because really causes the construction line end point to remain attached to that line, as if it were infinite, which makes sense, but not what I want.

I was just wondering if there is a way to define them as a single object, so when you attach relations, it would follow the line as if it were a single spline. 

And no, a spline really isn't an option here....I don't think. I tried it, but couldn't lock it down well enough to actually follow the configurations.