How can I continue a spline (without using tangent constraint)?

[deutirium]

Sometimes I need to extend a spline or delate a segment and redo it. When clicking on the fit point spline command, it sometimes (seeminly haphazardly) gives me the option to continue my last finished spline (maintaining curvature continuity). This is what I want to do, but can't find a way to repreduce this behaviour at will. Most of the time what I get is that I am starting a new spline that is simply attached to the original curve by a coincident constraint, meaning it is not continous. I could then add a tangent constrait, but this could lead to strange behaviour if the original spline isn't fixed and may cause me downstream issues when adding modifiers to solids created by this spline. Is there a specific sequence needed to continue a spline? 

I'm attaching a screenshot showing the behaviour I usually get (and not what I want) where adding a new spline to exisiting spline geometry by starting at the first spline's endpoint created a new spline that is discontinous