Model subject ID in differential analysis using fitFeatureModel

[K-Pimentel]

I would like to include subject ID in the design matrix of a fitFeatureModel as I am analysing data from a crossover study and it is thus useful to control for subject ID. As far as I can see the fitFeatureModel does not (yet?) offer the same flexibility as the model.matrix as accepted by fitZig()

I receive an error message when I attempt the analysis:
Can't analyze currently

Are more complex study designs supported by the fitFeatureModel() function or is this planned for the future? Thank you.