I did my own trial to edit an existing CSL, but I need help fine tuning it. I am pasting the csl below

I am having a problem with citation. A reference with only 2 authors is sometimes cited as (First et al., year) and sometimes (First & Second, year). Same thing with multiple authors, sometimes the first is written followed by et al., and sometimes a list of the first 4 or 5 authors then et al.

Where can I possibly edit the csl file to control this
Thanks

<style xmlns="http://purl.org/net/xbiblio/csl" class="in-text" version="1.0" demote-non-dropping-particle="sort-only" default-locale="en-US">
<info>
<title>Journal of Biomolecular Structure and Dynamics (new)</title>
<id>
http://www.zotero.org/styles/journal-of-biomolecular-structure-and-dynamics-new
</id>
<link href="http://www.zotero.org/styles/journal-of-biomolecular-structure-and-dynamics-new" rel="self"/>
<author>
<name>Rabab Toubar</name>
<email>rabab_toubar@gmail.com</email>
</author>
<category citation-format="author-date"/>
<category field="biology"/>
<issn>1439-1791</issn>
<updated>2012-02-07T01:46:04+00:00</updated>
<summary>
A style for journal "JBSD-new"
</summary>
<link href="http://www.jbsdonline.com/instructions-c4292.html" rel="references"/>
<link href="http://www.zotero.org/styles/journal-of-biomolecular-structure-and-dynamics" rel="template"/>
<rights>
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 License: http://creativecommons.org/licenses/by-sa/3.0/
</rights>
</info>
<macro name="editor-translator">
<names variable="editor translator" prefix="(" suffix=")" delimiter=", ">
<name and="symbol" initialize-with=". " delimiter=", "/>
<label form="short" prefix=", " text-case="capitalize-first" suffix="." strip-periods="true"/>
</names>
</macro>
<macro name="author">
<names variable="author">
<name name-as-sort-order="all" and="symbol" sort-separator=", " initialize-with="." delimiter=", " delimiter-precedes-last="always"/>
<label form="short" prefix=" (" suffix=".)" text-case="capitalize-first" strip-periods="true"/>
<substitute>
<names variable="editor"/>
<names variable="translator"/>
<text macro="title"/>
</substitute>
</names>
</macro>
<macro name="author-short">
<names variable="author">
<name form="short" and="symbol" delimiter=", " initialize-with=". "/>
<substitute>
<names variable="editor"/>
<names variable="translator"/>
<choose>
<if type="bill book graphic legal_case motion_picture report song" match="any">
<text variable="title" form="short" font-style="italic"/>
</if>
<else>
<text variable="title" form="short" quotes="true"/>
</else>
</choose>
</substitute>
</names>
</macro>
<macro name="access">
<group>
<text term="retrieved" text-case="capitalize-first" suffix=" "/>
<date variable="accessed" suffix=", ">
<date-part name="month" suffix=" "/>
<date-part name="day" suffix=", "/>
<date-part name="year"/>
</date>
<group>
<text term="from" suffix=" "/>
<text variable="URL"/>
</group>
</group>
</macro>
<macro name="title">
<choose>
<if type="bill book graphic legal_case motion_picture report song" match="any">
<text variable="title" font-style="italic"/>
</if>
<else>
<text variable="title"/>
</else>
</choose>
</macro>
<macro name="publisher">
<group delimiter=": ">
<text variable="publisher-place"/>
<text variable="publisher"/>
</group>
</macro>
<citation et-al-min="6" et-al-use-first="5" et-al-subsequent-min="2" et-al-subsequent-use-first="1" disambiguate-add-year-suffix="true" disambiguate-add-names="true">
<sort>
<key variable="issued"/>
<key variable="author"/>
</sort>
<layout prefix="(" suffix=")" delimiter="; ">
<group delimiter=", ">
<text macro="author-short"/>
<date variable="issued">
<date-part name="year"/>
</date>
<group>
<label variable="locator" suffix="." form="short" strip-periods="true"/>
<text variable="locator" prefix=" "/>
</group>
</group>
</layout>
</citation>
<bibliography hanging-indent="false" et-al-min="20" et-al-use-first="20" entry-spacing="1" line-spacing="1">
<sort>
<key macro="author"/>
<key macro="title"/>
</sort>
<layout>
<text macro="author" suffix="."/>
<date variable="issued" prefix=" (" suffix=").">
<date-part name="year"/>
</date>
<choose>
<if type="bill book graphic legal_case motion_picture report song" match="any">
<group suffix=".">
<text macro="title" prefix=" "/>
<text macro="editor-translator" prefix=" "/>
</group>
<text prefix=" " suffix="." macro="publisher"/>
</if>
<else-if type="chapter paper-conference" match="any">
<text macro="title" prefix=" "/>
<group prefix=". ">
<text term="in" text-case="capitalize-first"/>
<names variable="editor translator" prefix=" " suffix="," delimiter=", ">
<name and="symbol" sort-separator=", " initialize-with=". "/>
<label form="short" prefix=" (" suffix=".)" text-case="capitalize-first" strip-periods="true"/>
</names>
<text variable="container-title" font-style="italic" prefix=" " suffix=""/>
<group prefix=" (" suffix=").">
<label variable="page" form="short" suffix=". " strip-periods="true"/>
<text variable="page"/>
</group>
<text variable="collection-title" prefix=" " suffix="."/>
<group suffix=".">
<text macro="publisher" prefix=" "/>
</group>
</group>
</else-if>
<else>
<group suffix=". ">
<text macro="title" prefix=" "/>
<text macro="editor-translator" prefix=" "/>
</group>
<group delimiter=", " suffix=".">
<text variable="container-title" font-style="italic"/>
<text variable="volume" font-style="italic"/>
<text variable="page"/>
</group>
</else>
</choose>
</layout>
</bibliography>
</style>

Great. Thanks for the explanation. I couldn't find a paper with the new citation and the paragraph mentioned on the "instructions" is just not enough. They have an endnote zip file though. Is there a way I can load it in zotero or open it for comparison ? I haven't used endnote before. Please let me know. Thanks again

As you mentioned, it did not open the .ens and I got an error message asking to validate the code.
The bright side is I contacted the editor and he sent me the styles. Now I need to edit the et-al part so that 2 authors are ALWAYS listed first and second and never use et-al
- Six or more authors are ALWAYS listed as First et al.

Now thanks to you and the tips on Zotero website I know that I need to edit this line:
citation et-al-min="6" et-al-use-first="5" et-al-subsequent-min="2" et-al-subsequent-use-first="1" disambiguate-add-year-suffix="true" disambiguate-add-names="true">

Sometimes I feel it might be easier to use the trial endnote now..or even edit it by hand after removing zotero codes. However, I want to learn and I am doing good editing so far :)
Thanks in Advance
Rabab

[[Below is the details of the citation:]]

[[A work by two authors
Name both authors in the signal phrase or in the parentheses each time you cite the
work. Use the word ‘and’ between the authors’ names within the text and use ‘&’ in
the parentheses.
Research by Wegener and Petty (1994) showed...
(Wegener & Petty, 1994)
A work by three to five authors
List all the authors in the signal phrase or in parentheses the first time you cite the
source.
(Kernis, Cornell, Sun, Berry, & Harlow, 1993)
In subsequent citations, only use the first author’s last name followed by et al. in the
signal phrase or in parentheses.
(Kernis et al., 1993)
If two or more references of more than three surnames with the same year shorten to
the same form, cite the surnames of the first authors and of as many of the subsequent
authors as are needed to distinguish the references, followed by a comma and et al.
Kernis, Cornell, Sun, et al. (1993)
Six or more authors
Use the first author’s name followed by et al. in the signal phrase or in parentheses.
Harris et al. (2001) argued...
(Harris et al., 2001)
If two references with six or more authors shorten to the same form, cite the surnames
of the first authors and of as many of the subsequent authors as are needed to
distinguish the references, followed by a comma and et al.]]

Yes please Adam. I don't know how to leave this valid only for 3-5 authors and set new terms if I have 2 and a third one for 6 or more. I need to make sure the code is wOrking properly before I can share it on Zotero for future users. Any input is highly appreciated.

for future reference - the T&F style they now use is essentially APA 6th edition - I've redirected the style on the repository accordingly.