If you are just relying on the partition/grid fixings to locate the partition, this should not adversely affect the ceiling's structural fire protection, provided you ensure that the partition is not fixed to a main runner either side of the grid's expansion cut-out which would prevent it from activating in the event of a fire.
However, if you are also using the ceiling grid to provide lateral restraint to the partition then, in the event of a fire, this could contribute to the premature collapse of the ceiling system with the consequential loss of protection to the structure.
If it is this second reason why you want to provide the partition/grid fixings, you should speak to the relevant building control and/or fire authority and obtain approval before commencing the installation.