ECC Receiver system config change: Which way is good?

Hi,

I have 120 plus interfaces as IDoc receivers/sender running in production.

The existing ECC system [SAPabc] will be down for patch updates and we need to point different ECC system [SAPxyz].

Please let me know which way is better to handle this situation.

a) Change each and every receiver channel details with SAPxyz and receiver agreement in the ID component and once revert back to SAPabc once it is up and running.

b) Change the logic system name in the SLD and point the existing SAPabc system details to SAPxyz and rever back once the SAPabc system is back and running.

Much appreciated if I get the steps to change the system details in SLD. [not much worked in SLD 😔 ]

Thanks

Ray..