Quote from the Manual
Adding Faces
Once you have added new edges to a mesh, you will be able to fill in the gaps with new faces. You do this by first selecting all of the edges that surround where your new face or faces will go. Then you use the Edit->FillHoles command to fill them.
There are a few things to note before you start adding faces:
* Faces can only be added to complete connected loops of edges. If there are any gaps, no face will be added.
* All edges in the loop must not already be part of two (or more) faces. Only edges that are part of at most one face will be considered. You can tell how many edges an edge participates in by its color when selected.
* You can select a lot of edges and do a fill of the whole batch at once. Anim8or will start by filling any selected edge loops of length 3. Then it will fill those of length 4, etc. until no more faces can be added. This will sometimes create undesirable results and you will have to try again in smaller batches.
* You may have to apply the Edit->FlipNormals and the Edit->FixNormals commands to orient new faces properly after they are added.
So you may have to delete some faces in your mesh before you can add the new ones you need to add.
This limits your ability to make stuff alot. Why is this rule needed. Is it because of a memory issue with anim8or, or just that's how the system was created? The fact that edges can only be attached to a certain amount of faces limits your control over stuff like complicated buildings, models, charechtars, ect. So what's the point of it.
