My daughter has long beautiful hair that goes below her waist. But now she has lice. A little back story:

We moved to my husband's uncle's land. He has 4 daughter 8-14 yrs old. When we moved in a couple of weeks later my son and I went on a trip to Mexico. My daughter being in school had to stay behind with my husband. Well while I was down there the uncle's wife told me she was scratching and she checked her and she had lice but that she cleaned her. She also said her daughters had lice too. I said thank you and that I was very grateful. I thought that maybe she has gotten the lice at school or something. Well like 2 days ago I noticed my daughter scratching again. I told her to let me check her head and sure enough she had lice again. I was so pissed. A couple of days before that the uncle's wife was outside checking her daughters hair. I told my husband well now I know how (my child) got lice. So fast forward 2 days ago I told my husband that she was full of lice again and all he said was clean her because she's almost in school. My point is how do I stop her from getting lice? I don't want to cut her hair cause like I said it's long and beautiful and she's never gotten a cut before. And obviously I can't tell the uncle's wife to clean her daughters because their infecting mine because we lice in their land. So what can I do? Any special shampoos out there that can prevent her from getting lice again ?

Just a quick edit:, We moved in November 2018 and I went to Mexico in december 2019. She has been clean for 7 months until 2 days ago. Let me note I also have long hair so I would have gotten them if I hadn't cleaned everything but I did and she was also clean