The Employer insisted on a certain person to fill the project control manager role was to be named as a key person. The Contractor has subsequently removed the key person and decided that the role is not needed and therefore, no replacement is being offered. However, the role will now be spread across 3 people already on the project the QS, Cost Engineer and the Planner
24.1 says the Contractor is to employ each key person or employs a replacement, but in this situation the replacement is a group of persons.
What can the Project Manager do in this situation?
Interesting one. You would like to think that being option C the Contractor is coming up with the most effective way of managing the project which will benefit both Parties and maximise both Parties gain share (or limit pain-share). I would get round the table and discuss if you think that these other people can cover those duties effectively.
Not withstanding that, you could instruct them to have a single person - particularly when that was a specific key person. They are obliged to issue a replacement and you have to accept if they are equally qualified or experienced. You could review disallowed cost definition and see if any costs being incurred for not replacing the Key Person would be applicable.
Above all - both contractual and non-contractual just talk and try to come to a mutual agreement on how this role would be best filled.