You are right, it could be confusing. After Saheila didn't give me 3rd source point, I loaded my previous position before going to Elven camp and went for Almina quest instead. It didn't work either. Then I tried them both and it worked (first one didn't give me source point, but second did). I think this is a bug made by latest patch. It doesn't matter who is the source master, first one attempting to give you 3rd source point doesn't work.
Ok, makes sense now.
