Cshack if this helps you the picassos that you have behave just like any other Percula. I was under the impression that offspring between percula and ocellaris originally happened on accident when two pairs of each were spawning in the same tank, since I had read that somewhere before (on a forum where people answer other people's questions).
I have also had a fish store owner tell me that when a bonded pair of clownfish is broken up, they will sometimes not pair up with another fish, or it can be difficult.
I have two snowflake clownfish. One that I got from a sponsor, and one that I got from

PETCO! (And I spent under $40 on each one of them, I might add)
Mine are ocellaris. The larger one will basically attack the smaller one. If the smaller one twitches it's body (which I am assuming is to show submission to the larger one), the larger one will stop attacking it. I have been watching them closely, and I have seen two clownfish fight and one get killed before when helping somebody set up a new tank, so that's the only difference I can say that I know between fighting and showing dominance.
However I am not an expert and I do not know as much about the fish as you might think I do. I do agree with James though, you should stick with what you have, maybe consider buying your sister a nice clownfish from one of our great sponsors on here who will be willing to talk to you and at least attempt to answer your questions.