A party is under a duty, in a timely fashion, to:

(a) Supplement a response with respect to any question directly addressed to:

(1) The identity and location of persons having knowledge of discoverable matters; and

(2) The identity of each person expected to be called as an expert witness, the subject matter on which the expert witness is expected to testify, and the substance of the testimony.

(b) Amend a response if the party later obtains information upon the basis of which:

(1) The party knows the response was incorrect when made, or

(2) The party knows the response, though correct when made, is no longer true, and the circumstances are such that a failure to amend the response is, in substance, a knowing concealment.

(c) Supplement other responses, as imposed by order of the ALJ or by agreement of the parties.