Why is the direct object taking を in (1) and に in (2)? What are basic rules that drive these two sentence constructions?
'My aunt is counting on my father's help.'
'The farmers depended on sheep-farming as their source of income.'
I am not sure of the technical terms but there is clearly a bit more going in (2). However the farmers in (2) are relying on sheep farming in the same way that my aunt is relying on my father in (1).
I think (1) could be amended as (3) to comply with the same grammatical rules as (2):
'My aunt is counting on my father for support.'
but I still do not understand how/when/what grammatical rules are being used.