I will suggest sticking to the original as much as possible. You can do whatever your want after the 4 bars but for that 4 bars, stick to it. Better all use the same keys, the name phrasing etc. Keys can be modulated after the 4 bars if you want to. If there are too many variations in these 4 bars, it becomes meaningless because everybody will start to sound entirely different. These seemingly annoying musical limitations will ironically force us to be more creative, not limit our creativity.
In real life, it is like this. I remember arranging for my first musical - I don't agree with the writer's melody many times. In some places, I even thought it was unmusical. But because I'm only the arranger, I was "forced" to agree. Felt like having my hands tied behind my back. But eventually, it turned out to be an interesting learning experience for me. I had to creatively write for something I don't like and make it sound good. Sometimes, he would tell me "I don't like the sound of this part" even though I thought I arranged that part well - but I still have to change it.
