Use a Button to Create a Level 2

System Administrators can create a button that will allow users to create Level 2 records on the fly.

Steps:

On the Level 1, create a custom field of type Read Only – System Variables
In the Variables section, enter the following:

<script language=javascript>
function createNewLevel2(){
location.href="/Apps/app_editevent.jsp?appid=1234567&nextlevel=1&companyid=@companyid@&objectid=@opportunityid@&eventid=0";
}
</script>
<input type="button" class=Button value="Button Label" onClick="createNewLevel2()">

where:

appid = the application ID of the in which the Level 2 should be created
Button Label should be the text that should show on the button (e.g., "Create New Activity")
the other fields should be left exactly as shown:

companyid=@companyid@ will associate the organization associated with the Level 1 record on which the button was pressed with the new Level 2 record
objectid=@opportunityid@ will link the new Level 2 record to the Level 1 record on which the button was pressed
eventid=0 will create a new, blank Level 2 record

This Read Only – System Variables field can then be referenced in a list view: