Scene child blueprint location

So, I have 2 blueprints that I put into my scene, both character types. I then parent one to the other in the scene. What I want to do is be able to set or constrain the now local position of the child blueprint. The main reason I have this setup is so that I can have the parent follow a spline but the have the child still able to move in all directions but never get ahead or behind the parent (basically, this is on rails). Set actor location and set relative location seem to assume there is no scene parent, so these have not worked. Is there another node I can use or maybe someone has a suggestion of how I can accomplish this a different way?

bump, anyone?