Transcript for Texas custody battle fuels debate over transgender rights

Reporter: Rachel Gonzalez knows her family looks typical. But here in Texas she says they are a target. Every day is a fight to keep her kids safe. Specifically 9-year-old daughter Libby, who is transgender. We needed to be able to create a sanctuary where all our children feel safe and loved no matter what. Reporter: Rachel has reason to worry. Her close friend is at the center of a national firestorm, surrounding her transgender daughter we are not identifying. A custody battle which has gone from private family court to global headline. The central issue, how young is too young for a child to they split up in 2015 with shared custody of their twins. But trouble started when one of the kids began identifying as a girl. Georgia allowed it. She was specifically asking for their father to affirm her as a girl by allowing her to wear girls clothes and use the name and pronouns that she uses. And he refused to do that. Reporter: Younger got upset and filed for sole custody. I'm not trying to cross-dress my son and mislead him into thinking he's a girl, and I'm not pushing my son toward medical transition. Reporter: He sarlted a website and gave interviews about the custody battle like on the conservative website, life This is my son's life, and I'm not backing down, and I was not surprised at all that Americans stood up for my son. Reporter: But a jury decided 11-1 that he should not have full custody. Georgia should. The judge ruled the former couple should share custody. How often are you in touch? Well, right now, multiple times a day. Reporter: What's her state of mind right now? She is exhausted. It's really hard it to be, I mean, she receives at least ten phone calls an hour, she gets text messages, people sending her messages of hate. Reporter: That to her personal phone. To her personal phones. Reporter: That disapproval extending to some of the highest officials in Texas and on. Senator Rand Paul tweeted, we don't let kids drink alcohol till 21. People want to move the smoking age to 21, but we will allow a 7-year-old to have his life and body altered like this? This is child abuse. The president's son, Donald Trump Jr. Weighed in, agreeing, quote, this is child abuse. People need to start to stand against this bs. Enough is enough. But it was Texas senator Ted Cruz's tweet that angered advocates. This is horrifying and tragic for a young child to be subject to hormone blockers. In is a bold-faced lie. No prepubescent child is going through medical transition. There is no such thing as surgery or hormone replacement surgery for prepubescent children. It doesn't exist. It's really hard to understand and hear the senator of Texas call us child abuser. Reporter: A doctor says a grade schoolchild would undergo what's called a social transition, a medical transition comes later and only if they choose. For younger kids who are nowhere close to starting puberty, the transition will be purely social. And that may be that the child chooses to dress differently, chooses different names or pronouns, and really all that's happening at that age is a social transition. Reporter: Rachel says the misinformation has led to threats against Ann, who is a local pediatricain. They put a dead animal in front of the doors of her practice. Reporter: A dead animal at the place of business? Mm-hm. And last week. Someone had thrown a rock through the window while her children were at home asleep. It's been really, really difficult to watch. How do you feel about what she's going through right now. I think it might be very hard for her. Reporter: That's Libby, Rachel's 9-year-old daughter. Even she gets that her friend doesn't have support from both parents. And when you guys hang out, what it's it like? It's really fun. Reporter: Easy? Yes. Reporter: Do you guys laugh a Yes. Reporter: What do you laugh There is something nice about having a friend like you. Libby doesn't have a lot of friends in Texas that identify as transgender. Went under a new name Reporter: But there are other kids like 11-year-old max. Max's family has been at the forefront of the battle for transgender rights here in his mom amber says it began during a fight over one of those so-called bathroom bills. I finally realized max had been holding his bladder all day at school. And for me, that was an ah-ha moment. I sat him down, like, baby, are you using the potty at school? He's like, no. Why not? The honest truth was that he felt more comfortable going in the boys room. Reporter: At one point in 2016, amber invited conservative Republican state attorney general Ken paxton to dinner. Here's an opportunity. Come have dinner with us. When you get to know someone on a personal level, it's hard it to hate up close. That's the key. It's hard to hate up close. They were here for almost two and a half hours. Hey! This is really important. Next time a piece of legislation comes across your desk. Just remember us. Remember max, keep that face in your mind. Mm-hm. That's why we feel so betrayed, you know. He said he would. He said he'd remember. Reporter: Amber says she thought he understood their position, fwhu October, paxton's office released a letter saying the children at the center of this dispute are in immediate and irrevocable danger. We reached out to paxton's office. The response, I trust that dfps will act immediately upon our request, conduct a thorough investigation and protect this After meeting a mother like me and meeting me in my home, meeting my child, breaking bread at my table, engaging with my children, and then acting like families like mine should not exist, it's infuriating. Reporter: GOP lawmakers in three states, Georgia, Kentucky and Texas are proposing legislation banning puberty blockers or hormone treatment to anyone under the age of 18. In some cases it would be a felony. You can't say that we're going to remove it as a policy matter and hope you survive the next five years. I mean, that is just gambling with people's lives. Reporter: Chase works on transgender justice for the aclu. And in recent years has become a visible advocate. That is essentially the state coming in and saying, what we want is for transgender children to die, because they are disregarding all the evidence that says a child needs to be affirmed and saying we are going to block that affirmation in every way that we can. Reporter: Texas Republican Matt Kraus tweeted about proposing a similar bill there. 7 years old is probably a little young to make these decisions. I think there is concern with making these life-changing decisions at an early age, before these children fully understand the consequences and ramifications of their decisions. Reporter: The doctor says it's important for legislators to understand that some medications are not permanent. If they start to enter puberty and they have that distress, they may get a medication called a puberty blocker. That medication is reversible, and all it is, is a pause button. I always want to be well-manufactured on any piece of legislation I put out there. So absolutely, we want to see any and all statistics and evidence out there. Reporter: As lawmakers keep debating, the custody battle rages on, and another motion was filed, asking the judge be removed from the case and sole custody being given back to her. There were some media sources who decided to share that she had gone to school in boys clothes but that was not true. She immediately changed into girls clothes. Reporter: This issue has far-reaching consequences. It's not your life to live, it's your child's life to live. We thought we had an obligation to stand up for the community. Just follow your heart and follow your child's lead, and, you know, just live a life of love and, you know, it's, it's the easiest thing in the world. Reporter: For "Nightline," kblor yeah Rivera, Dallas, Texas.

This transcript has been automatically generated and may not be 100% accurate.