No agreement between the parties, their attorneys, or representatives, with regard to any matter involved in any proceedings before the department shall be enforced unless it be in writing, signed and filed with the hearings clerk as part of the record of the case, or it be read into the record of the hearing. This rule does not limit a party's ability to waive, modify, or stipulate any right or privilege afforded by this chapter, unless precluded by law.
4 Tex. Admin. Code § 1.7