That's basic band awareness. That also requires humility not to overplay. Some would call coloring outside the lines reharmonizing. I call it a hot mess if main keys, organ and aux all playing different arrangements. But, if you're by yourself it MIGHT be ok as long as you don't distract and/or throw off the singer(s).
Besides worrying about the vocalists you have to think about the audience you in front of!!! The average audience mostly aren’t musicians they not gonna understand nobody but you!!!
