Etta's sister (Mayberry), who supposedly ran into a tree and became crazy ever since, does not physically appear in The Land Before Time XIV: Journey of the Brave and is only mentioned in the following quotes:

Etta: Come on, Littlefoot. Cheer up. I had a sister once used to say, "Just when things get darkest, that's when you look for the light." Unless, of course, it's too dark to find it.
Etta: (singing) So listen to my sister, mister, come on and look for the light.
Etta: Well, that's what my sister used to say. But you can't exactly go by her. She ran into a tree once and been a little funny in the head ever since.
Etta: Heard ya the first time, but we're looking for a way out. Like I was saying about my sister...
Etta: I like the way you think, Littlefoot! She had a lot of sayings, my sister. Like... You know, "Don't use your tail to sniff the trail." Oh, that got me every time.

Character is owned by Universal while the colors and name are owned by  DinoFun and I own the design.