You can sort groups using the group sort expert.
This can only be used for group values that are (or could have been) created using the insert summary function.
this will allways sort ALL groups ascending or descending on the value you selected.
I do not know of a way sort by both group summary data and alpha.
Dependingh on what you want to show your user or the purpose behind this you may want to just use a top N chart in the RH to replace the sorting?