Try looping through all children as suggested but doing a check on the entity class before trying to alpha - if the entity is a mesh then alpha it - if its a joint(pivot) then no.
http://www.blitzbasic.com/b3ddocs/command.php?name=EntityClass&ref=3d_a-z
You could also try another approach - instead of parenting the second mesh to a joint just position and rotate it to the GLOBAL x, y and z coordinates and pitch,yaw,roll values of the joint each loop.
The second mesh then remains an individual entity.
http://www.blitzbasic.com/b3ddocs/command.php?name=EntityClass&ref=3d_a-z
You could also try another approach - instead of parenting the second mesh to a joint just position and rotate it to the GLOBAL x, y and z coordinates and pitch,yaw,roll values of the joint each loop.
The second mesh then remains an individual entity.