Hi rb,
I am having a little trouble following your question here but I will try to assist.
I think what you are asking is how to create 2 groups from 6 different possible data responses that appear in the same field.
Create a formula field as "Grouping" (or whatever you want to name it) as:
if {table.fieldtogroupon}="current assets" or {table.fieldtogroupon}="case & cash equiv" or {table.fieldtogroupon}="other assets" then "Assets" else "Liabilities"
Now group on this formula filed and it will split the data into these 2 categories accordingly.
Hope this is what you are looking for. If not feel free to clarify.