looking for group time series examples , I am working on two hierarchies and interested in interactions also. 
Couple of challenges I am facing - 
1. I have 36 months data and many of the series has leading NAs as not for all the series data is observed from the beginning
2. If I have to try any other time series model than default ones ( ets, arima ) how that can be achieved
3. while using the accuracy.gts function getting the error - 
Error in `colnames<-`(`*tmp*`, value = unlist(labels[levels])) : 
  length of 'dimnames' [2] not equal to array extent
Manually I checked the dimensions and they are the same so not sure about this error

Any pointers on this will really help.