The xml structure must be:
<?xml version="1.0"?>
<dust version="2.2.0">
<group attachto="Body1">
<particle>
<pos>-62216902732.591;4117459770.55927;-29344645.2920446</pos>
<vel>-6807.46702343351;-102713.587828491;-1148.65755202698</vel>
<color>207;216;255</color>
<coloralt>154;174;255</coloralt>
<size>0.1</size>
</particle>
</group>
</dust>
As long as you type the particle tag in full, you can create as many as you like changing the
<pos> using a text editor.
The only catch thing is this parameter of the
group tag:
attachto="Body1". In the example this is attaching the dust to the body called
Body1. Is always best to attach the dust to some bodies nearby or to very far away unnamed hidden ones.
The reason is because if you leave only dust in a system it will vanish next time you reload. It will also vanish under some other conditions even with bodies present. So create as many as you want, the way you want, save the sim. Open the saved ubox with winrar (or the building file tools) open the dust file, preferably using a decent editor, like ultraedit or 010 editor, and find and remove all the <group> and </group> tags leaving only the first and last. Now go to the top, and add the proper attach parameter to the group, attaching all the dust created to this single body. Save and load.