Free-to-use parenting style questionnaire I'm working on a master's thesis in UX design that I might want to turn into a commercial project later on. The subject matter is use of Nonviolent Communication (NVC) in parenting.

For the research phase, as part of a screener, I want to get a sense of a person's parenting style. I've been looking for questionnaires on evaluating parenting styles and found the Parental Authority Questionnaire.

However, this questionnaire was made to be evaluated by children, not by the parents themselves. Is there an alternate questionnaire for them? Would I be able to use its questions in my screener? What are the regulations regarding using questions from a different questionnaire?
There are a lot of parenting style questionnaires. Without knowing what dimensions of parenting style are of key interest, how long you want the questionnaire to be (e.g., trade-offs between validity, reliability with ease) and such, it's hard to recommend a particular one. You can see several from the parent perspective here: https://www.google.co.uk/search?q=parenting+style+questionnaire

As to regulations, you may need to contact the authors or journal about whether the scale is permissible for commercial use. I've only ever used scales for academic use.