Hi Carolina
Mustafa has taken you one level near to the solution...
If your project has postings with, say, 2 Primary cost elements and you can A to settle to CC and B to PSG, its possible... You have to set up Source Structure with assignments 10 for A and 20 for B
Now, when you maintain settlement rules, you will maintain 2 rules instead of 1... In Rule 1, select Assignemnt 10 and Receiver object as CC
In RUle 2, select Assignment 20 and Receiver object as PSG... Note that you will have to enter the characteristics you want to generate the Prof segment... If you want it to be automated, you will have code some user exits (Tedious)
Br. Ajay M