Retrieve and Change Point Data in Custom Application

Hi Experts,
I have loaded 2 datasets. One with 3 components (RGB) and the other as 1 component (A). I want to combine these two to form a single dataset of 4 components (RGBA). I implemented this using a programmable filter in ParaView GUI using numpy and stacking them. But I want to do it in a custom application. Is there any way I can efficiently retrieve the point data arrays and append them in C++?
This is how I read in the data:

pqPipelineSource* pipelineSource = pqLoadDataReaction::loadData(files, "sources", "PVDReader");