If you are using Revit 2012, and notice that some nested families [such as windows and doors] don’t regenerate with changes to the host family, I have included some additional information. This scenario would cover a nested-family which contains parameters associated to a host-family parameter.
For example, the host family parameter for “Width” is associated to the nested family parameter for “Width” in order to update both dimensions.
1. Ensure you apply the Revit 2012 Web Update 1. There was an improvement in nested family regeneration with the latest update; relevant links are attached:
2. Next open the host family where you noticed the nested family retaining the original dimension. This is the main symptom of this scenario; you update a parameter value in the host family but the nested family does not update [and remains the original dimension].
3. Make a small change to the family. For example add a model line, and then delete the model line. This is enough for Revit to detect the family has been updated. Load the host family back into the same project, and choose to overwrite when prompted.
4. The host and nested family should immediately update. Then moving forward this process should no longer be necessary.
I have included a video of the scenario and workflow below: