Based on Intel specification the maximum support you have on the Intel HD 4400 is 3 displays.
A CSV-5400 will not be of use to you as the GPU is not capable of driving more than 3 displays through the DP 1.2 port. Multiple DP ports on your docking station will not mean that you can drive either 3 or 4 displays with a MST hub, display support is limited by the GPU used. For example a Radeon R7 or R9 series is able to drive 6 displays with a combination of a MST hub and native video ports on the device.
You can find more information about your GPU under display support here