I'm not sure if this is the relevant place so feel free to move or pin as needed. I propose using this thread on making notes when looking at adding new avatars. Thusly: -

1) Most summoned animations will begin with the xxxgu and xxxgue animation cycles. These are the "get up" animations. Without them, the summons will cause a game crash.

2) If you're trying to add an animation which doesn't have such an animation cycle, a good work around is to use a null bam file. Create a bam with the above naming conventions and slap it in your install/override. The game doesn't check for the bam content, it just checks for the bam itself and plays that out. It's only a named bam absence that will cause a game crash.

3) There doesn't appear to be a limitation on how many frames there are in each cycle. In working with bams, I've exceeded the original frame count of the deleted animation and nearly doubled it. It works fine although I've not tested this at length.

More as I get them.