This should be possible. At some point (long time ago) CINT did not support constructors with >9 arguments of the same type, which is
why only ctors with 1 through 9 args exist for RooArgSet. But this is the only place where this ‘9’ limit shows. A RooArgSet can have an arbitrary number of arguments, and no RooFit code anywhere has any limits on 9 parameters. Here is an example of how you get around: