Copy nonlinear models

Is there any function to copy a nonlinear model?

Also, I want to know how to combine two models, e.g., I want to combine the variables and constriants from two models into a new model and create a new objective using the sum of the objectives. I can copy the contraints using MathProgBase.constr_expr(d,i) , but how to combine the two nonlinear objective?

No. PRs are welcome.

You can accomplish this by using the raw expression input form.