If the accounts of all the three companies are maintained by the same office of the RPF commisioner, there wont be any problem in transferring the entire accumulations to your new account straightaway.

Even otherwise, when your transfer request in FORM 13 goes to the respective PF authoritities of Company B , they will not effect the transfer unless the earlier request for transfer from Company A to B is effected.

However, there is nothing wrong in ensuring whether the Pf accumulations is already transferred to B company or not before submitting the necessary transfer form (FORM-13) to Company C.