Kabir's entry in VR mansion must be Vansh's plan as in initial episodes Vansh said Riddhima " ye mansion meri duniya h ya jo bhi hota bhagwaan ya wakt decide nhi karta Vansh decide karta h" so it may be a part of his plan and ones inside the mansion Kabir can't do anything against Vansh to show himself goody goody he won't disclose about Ragini incident and Vansh(Vihaan) will act as of memory loss. Inside the mansion he will handle both AnuBir of his own.
I am still stick to the fact that Vansh planned his fake death with Riddhima and Mishra involved in his plan and Vansh is only Vihaan.