Short and sweet...they don't mix unfortunately. When they created the capability they either missed the fact that legends didn't support them or they decided the feature was more important than them working in Legends to hold them back. I'm glad we have FBF's. I'm not glad about or happy with the Legend feature set.
Legends are compromised by (at a minimum):
- Inability to transfer them between project files.
- Face Based Families do not work in them
- Tags cannot identify the elements displayed in them
- A sheet includes a legend in its "Scale" display evaluation.
An element in a Legend view should be "equal" to a real element but not affect quantity. That means tagging as well as dimensioning. The current implementation sacrifices bIm for graphic representation as well as ease and consistency of use.