How to merge multiple 'having' clause relation in rails 3

If i remove any one of scopes having clause then the above action
works perfectly . Is there any way to like- @model =
Model.vacant_list(daterange) and then remove the active record
relation and then apply @model.amenity_type(term). I tried lots of
things but didnt find any solution for this.....
Full question listed here
http://stackoverflow.com/questions/6986561/how-to-merge-multiple-having-clause-relation-in-rails-3