Can I set the value of field for a custom list based on which custom form a user chooses?

New developer. Be gentle, please.

Constraints: I am using SharePoint Designer and SharePoint 2010 behind a firewall so I can’t upload pretty much anything without going to my helpdesk and getting a tech person to do it for me.

Situation: We track “Activities”. There are many points of origin for an Activity request. Different clients give us different information and are going to need custom forms (custom new item forms created through SPD). However, all these forms will create new items for the same custom list, “Activity Management”, and I have workflows already in place to create a new Activity Number each time one is created based on a batch of other stuff that is probably not super relevant. All these workflows were designed for only 1 custom form, though.

I need to create a second form and have it not trigger some of my workflows at this time. My idea is to have my new custom New form auto-fill/pre-populate on load/etc a field that identifies which form it is. Then I just have to make a condition at the top of my workflow to not activate for that form. Then we can do it later by changing that field to a value of my choice, now triggering the desired workflow.

I just can’t figure out how to simply set the value of a field within the html of the form – not hiding anything, not making the field a cascading anything, nothing fancy. I have a default inside the SharePoint List Settings that is “No Form” for when I do things manually. Once I figure this out for this form, I’ll imitate it for each custom Change or Activity request. And we can have as many entry points as my bosses need…

Potential Paths to a Solution: Can I do this within table row itself?

               <tr>                     <td width="190px" valign="top" class="ms-formlabel">                         <H3 class="ms-standardheader">                             <nobr>Form Used</nobr>                         </H3>                     </td>                     <td width="400px" valign="top" class="ms-formbody">                         <SharePoint:FormField runat="server" id="ff95{$  Pos}" ControlMode="New" FieldName="Form_x0020_Used"  __designer:bind="{ddwrt:DataBind('i',concat('ff95',$  Pos),'Value','ValueChanged','ID',ddwrt:EscapeDelims(string(@ID)),'@Form_x0020_Used')}"/>                         <SharePoint:FieldDescription runat="server" id="ff95description{$  Pos}" FieldName="Form_x0020_Used" ControlMode="New"/>                     </td>                 </tr> 

Or, maybe there is a really nifty javascript thing that could be used…

<script type="text/javascript" language="javascript">     function setff95() {         Something     } </script>