First off, woodwoox, what are you talking about with a wall? I cant find any reference in this post to a wall so I don’t know what you mean and can’t help ya.
As for setting something on fire and making the fire grow bigger, you could just make the object you’re melting a softbody, then have that be a surface emitter and get the softbody to melt. Then you can key different attributes of your fire to grow as it melts. Another excellent thing you can do if you want the fire to crawl on the object as it burns, say, the fire spreads down as it melts or something, then you can use texture emission on your object so the surface emission only comes from a certain part. This only works for NURBS surfaces though so if it’s polys, then you cant use surface emission
I’m not totally clear as to what you meant with this statement “Cause when i select a object with a few objects aside it and I set the selected objects on fire and animate it then the other objects are unaffected.” so if you could explain it a little further I might be able to give a more specific solution as well.