As per my understanding, you want to place all your DDR signal in Bank 6 and move the RUP/RDN from Bank 5 to Bank 6 as well. Is this correct? Please let me know if I understand this correctly.
If my assumption correct, kindly please refer to below explanation about the RUP/RDN placement :
I can move the RUP and RDN signals from bank 5 in a couple of pin of DQS2 group and ay yhe same time I'll loose the DQS2 functionalities. Is this correct. --> Yes, you're right.
Please also take note on the following impacts on your DQS groups when the RUP and RDN pins in devices being used as DQ and DQS pins when they are not used to support OCT:
1) If the RUP and RDN pins are part of a ×4 DQS group, you cannot use that DQS group in ×4 mode.
2) If the RUP and RDN pins are part of a ×8 DQS group, you can only use this group in ×8 mode if any of the following conditions apply: