Nothing you need to do in Texas. It's her gun, she can sell it. After the original sell there's nothing that would track the change of ownership amongst private citizens.
I was in a shop here in Dallas when a girl came.in and asked if the owner would do a transfer for her. He said yes, then asked if she knew the guy, she said it was her boyfriend. "Why not just give it to him?" She said the gun was originally bought in Chicago. He said "you're in Texas now, if you want to give it to him, just give it to him"
Sent from my SAMSUNG-SM-G890A using Tapatalk