co-sited cell handover

hi erveryone,
it’s a Ericsson parameter problem.
i have learnt that when the parameter CS equal to yes, the neighbouring cells are taken as co-sited cells. i am confused about the significance of this parameter. when handover happens between co-sited neighboring cell, is there any difference. like MS or the network can omit some signalling message. AND IF TWO CELLS ARE NOT REALLY CO-SITED,BUT CS IS SET TO YES,WHAT WILL HAPPEN.

TWO cells are co-sited,but one have RPT Repeater ,that meaning TA are significantly different, CS should set to yes or no?

thanks.