When I have multiple 'remote' clients writing data, I am trying to find a way to recognize which client data I am writing to the underlying storage.

Appreciate if anyone in this list can point me in the right direction to access remote client UUID.

Probably the best way to do this is to set the "JobID" on the client, and then check "lctl get_param {mdt,obdfilte}r.*.job_stats" on the servers.  You can find a detailed description of JobStats in the Lustre Operations Manual.