bvp4c with more boundary conditions than equations

I'm working an orbital mechanics problem where I have four differential equations with four time dependent variables (radius and angle for position and radial and tangential velocity). I also have a parameter free to change with time (thrust angle).

I want to be able to solve a TPBVP (two point boundary value problem) with set start and end points for all four variables (i.e. a starting position and velocity and final position and velocity) and allow the thrust angle at each time step to be varied to build a path between those points.

The problem I'm having is that Matlab is telling me I can only input the same number of boundary conditions as equations (4), but I want a total of 8 boundary conditions. Is there any way around this? Or is the bvp4c/bvp5c function simply not capable of what I'm trying to do?