I need to save slices twice

I have a variable declared in an edit context that decides the value of a non edit context variable, call them m_event and m_eventId. Both are declared in the serialize context. I have a function that decides the value of m_eventId after m_event is set using a changenotify attribute in the editcontext. The problem is when making a change to m_event in the editor and saving the slice, only changes to m_event will be saved in the slice. I will need to save the slice again for m_eventId to be saved in the slice file.

Does it look like I need to flag m_eventId as having been edited somehow?