title: How to create a sharepoint list column that links to another list that is editable
body: <p>I'm not sure if the title is a proper descriptor of what I'm trying to achieve here, hopefully it's close enough.  I'm not a SharePoint expert, but I'm comfortable with creating forms and workflows as necessary to get something like this to work.</p>
  
  <p>Basically, I need to have two separate SharePoint lists that are linked together, but one list needs to have row level security to hide data from other users that shouldn't see it. I need the column that is being linked to be an editable text box though, rather than a simple lookup field.</p>
  
  <p>For example:</p>
  
  <p>List A</p>
  
  <ul>
  <li>Customer (text)</li>
  <li>Description (text)</li>
  <li>Sales People (person, multiple selections allowed)</li>
  <li>Expenses (linked field)</li>
  </ul>
  
  <p>List B</p>
  
  <ul>
  <li>Customer (text)</li>
  <li>Expenses (number)</li>
  <li>Created by (just a reference that the sales people would actually "create" each row here)</li>
  </ul>
  
  <p>Essentially, multiple people can be assigned to a customer in list a.  The "sales people" are assigned by another user who actually creates the item for list a.  I need to be able to have the people who are assigned as "sales people" to have a text box where they can enter their expenses, but on an individual basis, that would then be stored in list b with row level permissions to prevent them from seeing each others expenses totals.</p>
  
  <p>List B would be able to show each sales person their full list of expenses across all the customers they are connected to, but not be able to see each others expenses.  It's not a problem if the person creating the item for List A ends up with items in List B that are 0, but I need to be able to have the Expense field be an editable text box from a form that allows the sales people to enter their total expenses for that customer.</p>
  
  <p>If I was building a custom application, this wouldn't be difficult to do, but I can't for the life of me figure out how to do this in SharePoint, or if it is even possible.</p>