Tex. R. App. P. 6.1

As amended through April 30, 2024
Rule 6.1 - Lead Counsel
(a)For Appellant. Unless another attorney is designated, lead counsel for an appellant is the attorney whose signature first appears on the notice of appeal.
(b)For a Party Other Than Appellant. Unless another attorney is designated, lead counsel for a party other than an appellant is the attorney whose signature first appears on the first document filed in the appellate court on that party's behalf.
(c)How to Designate. The original or a new lead counsel may be designated by filing a notice stating that attorney's name, mailing address, telephone number, fax number, if any, email address, and State Bar of Texas identification number. If a new lead counsel is being designated, both the new attorney and either the party or the former lead counsel must sign the notice.

Tex. R. App. P. 6.1