Use semicolons and commas as multiple citation separators under different conditions

Hi, I am trying to figure out the setting in Endnote to use semicolons and commas to separate multiple citations under different conditions.

Specifically, I’d like to separate author groups with semicolons when having author groups (i.e., two and more same author, same year citations), but still use a comma as a separator when not having author groups. For example:

 (Kevin et al. 2001a, b ; Jones et al. 2005 ; Adams et al. 2007, 2008) when we have author groups; but when we do not have author groups, it would look like this with comma as multiple citation separators (Kevin et al. 2001 , Jones et al. 2005 , Adams et al. 2007).

A screenshot of the above requirement of the journal I am interested in is in the attachment.

I don’t believe this is an option.  You can hide the year for the second one (but you need to know which one will be second based on the sorting criteria, and type in " , b"  (the comma space b)   in suffix of the first.  

I also don’t think you can swap the semi-colon for comma in the two different instances.