Starting a story but with something already done?

Hello, I hope this isn't the wrong board but I don't think I could find any other suitable areas. I greatly enjoy writing fanfics about MMO's with stories with their unique goals. I done a very long series about an adult story related to Ragnarok Online and I thought I'd try to do something with futanari in it. The thing is I kind of want to use the characters of this story despise the fact I never put futanari before.

My question is, if I started doing alternate "episodes" of the original story and non-canon sidestories related to it, would it actually make sense or would it be frowned upon?