Append workflow changes to existing content

Question

I have a workflow that updates a lookup column in another list when conditions are met.

The problem is that the column allows multiple values, but the workflow is replacing any content that already existed.

I'm looking for a way to add the new value onto the end of the currently existing data.

I've tried to edit the xoml of the workflow, but SP designer will not allow me to do that.

Answer 1

You can do something like:
Passing Multiple Users As A String to a Person/Group Lookup Column in a SharePoint 2010 Workflows

A Person/Group Column is also a Lookup column, so you can prepare a proper string like
[Id];#[Title Of ListItem];#[Id];#[Title of ListItem]

I hope this works!