Blender animation control

[Luna Barak 17]

Hello, I am very new in making animations with Blender so I am probably making a dumb question but I have a little issue.
I have a drinking animation where only the left arm and hand are involved, in Blender everything else is correct but when I import in SL the body have light unwanted movements, in this case the other arm lightly move down. Checked the Blender closely I found no issue, no keyframes that show a change in the arm that infact should stay firm.
I remind with Qavimator I was avoiding unwanted movements by setting a value different from 0 for each bone but in Blender I dont find a way for that and I am not even sure it is the same issue.
Anyone has any clue about this? 
 

[OptimoMaximo 1,130]

You are not mentioning anything about the exported file format you-re using

Assuming that you're using Avastar with its .anim exporter, you should make sure that the arms that need to stay firm have a rotation change between first and second frame of your animation, in order for the scripts to store it in the file. Otherwise it will just skip the limb entirely and let the animation slot empty and, as consequence of this, in SL that arm will keep being animated by one of the animations that is playing already, no matter if your animation is higher priority.