Of course! I do not own these sims and the stories I write are absolutely not cannon for anyone but me.
I’m a firm believer that those sims were there for us to play and I have no issues with others creating stories for them at all. In fact if you do I would love to see it! Some of my favorite blogs here also involve premades.
So go ahead give them some love and I hope you have fun! I’ll be over here at my desk chanting “One of us!”
