How to merge multiple PVD and VTP files

ParaView Support
6 
 import os                                                                   
 import glob                                                                 
 os.chdir('path/to/your/folder')         
 for file in list(glob.glob('*.pvd')):                                       
     OpenDataFile(file)
 for file in list(glob.glob('*.vtp')):                                       
     OpenDataFile(file)

https://kitware.github.io/paraview-docs/latest/python/
https://www.paraview.org/Wiki/ParaView#Python_Scripting