Incremental Merge Strategy with no Update case

Hello, i wonder if there is a way to load a satellite on BigQuery with the incremental Merge strategy. In my point of view i dont need a
when matched then update set… part
if my merge condition is source.hashkey = target.hashkey and source.hash_diff = target.hash_diff
i only need to insert new records. In case of update ( hash_diff is different ) its a new Sat version as insert.
Is there a way to config the Sat Definition only use the when not matched then insert
Thank you very much