Same authors, multiple years - omitting author names and sorting

Hi all,

I have here what is probably once more a problem that cannot be solved in endnote. For a paper, I need the citations sorted by year and then author name which is easy to do. Whenever there are multiple authors with the same name, I need them grouped together irrespective of the year. Two problems occur

(1) Whenever there is a publication that was published between two publications by the same author, the publications are listed separately.

For example: I NEED : [Hack, 1957; Sklar and Dietrich, 2001, 2004, 2006 ; Whipple and Tucker, 2002; Turowski et al., 2006;].

I GET : [Hack, 1957; Sklar and Dietrich, 2001; Whipple and Tucker, 2002; Sklar and Dietrich, 2004, 2006 ; Turowski et al., 2006;]

(2) I need publications grouped together as soon as the abbreviated author list is the same. However, I only get it whenever the full author list is the same. 

For example: I NEED [Turowski et al., 2006, 2008, 2009;]

I GET [Turowski et al., 2006; Turowski et al., 2008; Turowski et al., 2009;] because the co-authors in these publications were not the same.

Is there any way to include that in the style sheet? I fear not but manually changing all citations will be a pain