hadd TH1::fFunctions

Hello

I add TObjStrings to TH1::fFunctions and write histograms in file. This works fine on a single file, however after merging several files with hadd the fFunctions is empty. Is this a feature? Is there any way to merger fFunctions of histograms?

Is there any other/better way to add some book-keeping information to histograms?

Thanks,

      Margar

P.S I am using ROOT 5.26/00e