hello. i m going to do a big work with particule fio a video clip an d i need a little help.
I got few question or limitation that i need to solve.
First is that possible to animate growth of particle based on black and wite map or based on the particle edit mode.
second if i do a cloud. with some rain, (particle emiter) is that possible to make that cloud being emit from an other particle emiter and still see the rain from each new cloud?
I m also looking for a way to set up a stellar systeme. one sun emiting few planette emiting few moon and each one getting a gravity systeme.
if someone get a systeme that work?
thanks for your helps
dag
Will do my best 
The emission location? Yes. http://wiki.blender.org/index.php/Doc:Manual/Physics/Particles/Controlling_Emission%2C_Interaction_and_Time
No.
I’m not sure whether you are trying to use particles for your third question?
HTH
Thanks for the response.
The second question is about a particle emitter emiting a particle emitter.
I got a raining cloud that emit rain and i want a plane that produce (emit) some raining cloud based on the first cloud that i set up.