I have a form that calls another form. The called form is to help the user figure out the value of one of the fields in the main BO. The called form actually updates the data in the main form's BO. I'm wondering if there is an efficient way to update either just the single column in the main form's BO or even just the single row?



If I refill the BO, I will also have to refill a bunch of child BOs, so there will be a performance hit.

I don't know of a way to get the data into the other business object other than calling the Fill() method on it (except maybe the CopyDataFrom() method if you already have the data local).  However, if you are trying to tie the data in one business object to the value in the field of another business object, you might look into using the FieldPropertyChanged events on the business object.  You can turn them on for the business object by opening the properties for the business object in the BOMapper and clicking "Show Advanced Options."  Both UniqueEventForEachProperty and SingleEventForAllProperties would work for you, I think.