You can use Actions (conditional logic for your giving page) to allow your donors to give in memory of someone or something.
First, set up all the needed fields on the page.
In this example, I'm using a checkbox field and two text fields to collect the giving information.
Select Actions and set up a new action.
Set up an action to SHOW the necessary fields when they opt to give in memory of... It will look like this:
Save the action. You can test to make sure it's working in preview mode.
