I have four explanatory variables and one independent response Y. Three of the explanatory variables (X1, X2, X3) are just measured in the experiments. However, the forth one is computed using a function where I am using varibales X1 and X2, hence it is not independent of them. I want to use GLM to model Y as a function of X1,X2,X3,X4. More importantly I want to know if any of those four variables are more "important" in modeling Y. Hence I have to include all of them in my model.

I was wondering if that dependency between X4 and X1,X2 causes any problem when I am using GLM?

I have four explanatory variables and one independent response Y. Three of the explanatory variables (X1, X2, X3) are just measured in the experiments. However, the forth one is computed using a function where I am using variables X1 and X2, hence it is not independent of them. I want to use GLM to model Y as a function of X1, X2, X3, X4. More importantly I want to know if any of those four variables are more "important" in modeling Y. Hence I have to include all of them in my model.

I was wondering if that dependency between X4 and X1, X2 causes any problem when I am using GLM?