Hi,
As per standard system behaviour you will not get the splits while WPBP is been changed.
But if you want to do the split in the IT14 and IT15 then you will custom processing type in PC47 and assign all the necessary wagetypes of IT14 & IT15. After that you have to modify X011 pcr and write below code for suppose Z is the custom processing type in PC47.
Z
OPIND
ELIMI A
WPBPC
Check and tell me.
Regards,
Sankarsan