Nobody knows you "cheated" except yourself.
Why don't you go into challenges with a mindset more along the lines that the challenge rules are guidelines to help drive your story and give you ideas of what goal you're working towards and let it play out the way you want. And if that means veering from a rigid set of rules to make it more interesting and fun to play, then that's what you should do. Don't feel guilty!
There's a challenge I saved but I don't want to actually "do" the challenge per se, but I liked the set up of the families as a suggestion and I'm going to attempt to play rotationally for the first time with these unique and diverse couples in the same neighborhood.
It's called the Ultimate Couples Challenge, you can find the rules here if you haven't heard about it before.
https://modthesims.info/showthread.php?t=413723