I told my mom about wanting to get this surgery and other surgeries (notably infra orbital rim implants).
My parents never assisted me financially in my previous surgeries (hair transplant, gynecomastia removal), but I still felt the need to tell them. I told her before our discussion that I have many problems and that I am not comfortable talking to her about them because I often feel like she doesn't support me neither emotionally nor financially and telling her just ends up creating more problems. We argued for a while but at some point she was willing to listen. I don't expect financial help, I am fortunate to have a very high paying job right out of university. Despite this, part of me felt an urge to tell my parents, but part of me also felt like telling them would be a huge mistake.
When she was ready to listen I told her about how I felt and why I wanted to do these cosmetic surgeries. I told her about the recovery time, success rate, safety, etc... I feel like telling my mom was a very good decision. Nothing has changed, but now I feel more honest and my mind is free from another worry "what if my parents find out". I also feel like I can get emotional support if I need to.
I just felt like I had to share since I read many posts saying "don't tell your parents". My parents are religious and not exactly the most open to cosmetic surgeries, but if you are willing to really and I mean really open up about all your problems without getting angry, then I think telling them is a good idea.
My current plan is to go from 177 cm to 186 or 187 cm via quadrilateral (surgeries 3 weeks apart) limb lengthening.