Custom Activity Creator: How to add a new parameter

[carlor]

Greetings!

I’ve inherited a Custom Activity library created in Visual Studio with the Custom Activity extension. I now want to add another parameter/field to the activity. Is there a way to do this through the extension or is it only for creating NEW activities? I’ve tried adding manually but have run into problems trying to update the designer file (displayed UI).

Thoughts?

Thanks,

Carlo.