Eval function trouble when avoiding attach into package

Hi, and welcome!

Thanks for the reproducible example, called a reprex. Always helpful.

best_migramod calls fit_migramod; after you initially capture x \& y with

x <- dataIn[, 1]
y <- dataIn[, 2]

the call to fit_migramod is

valSim <- fit_migramod(dataIn, parameters_0 = param_0, model.rc = model.rc)$values

which hasn't been modified as it was earlier.