I found a manual way of doing this that others might find helpful. I only found out I could do this by accident!
Turns out if you edit a condition or action, if you click the 'back' button it doesn't go back to the event sheet, it actually goes back through the settings of the action/event, all the way back to the object type. This lets you change what object type it is using without recreating the action. I wonder if there's others who didn't notice this either <img src="smileys/smiley4.gif" border="0" align="middle" />
So I renamed the instance variables I had, added it to the object family, and then went through all my events/actions and modified the type of object they are associated with. Took a few minutes of work, but it works.
If anyone knows of an easier or different way, please do share.