According to Gerald Lebovits, in the NYSBA Journal, July/Aug. 2006 at 53, if you want your writing to be more concise, spot and remove nonstructural relative clauses.
(1) Our widget group believes its customer owes them $500,000.
(2) Our widget group believes that its customer owes them $500,000. The relative clause must be included because it is part of the structure of the sentence. The group didn’t believe the customer, it believed the relative clause phrase.
(3) We hope that the environmental group will appreciate the cost.
(4) We hope the environmental group will appreciate the cost. The relative clause should be stricken, because it is nonstructural. No one “hopes” a group.
You can strike the nonstructural “who,” “who are,” “who is,” “whoever,” “whom,” “whomever,” “which,” “that”, “that were,” and other variations.