You might be surprised at how common this is - there are loads of MNers who have had similar problems with their children.
It took my dd 15 months to poo in the toilet after she was dry and out of nappies during the day - she was almost 4 before she cracked it. She used to get hysterical and scream the place down if we even suggested using the toilet, and she would only poo in a nappy, in one particular place (not the toilet, unfortunately!), and at one particular time of day. My advice would be not to do anything at the moment - just let her become comfortable with the idea of using the potty/toilet for a poo in her own time.
If your friends would feel happy letting their dd have a nappy for a poo (we did, and it didn't confuse dd - it actually made her more relaxed about things) then I'd say let her know that she can always ask for a nappy for a poo if she wants one. Or maybe even put her in a nappy and ask her to try for one, if she goes at a particular time every day. It helps to see training for wee and for poo as two separate processes - the fact that she is ready to wee in the potty doesn't automatically mean that she's ready to poo in the potty.
Regardless of whether she's physically ready, if she isn't emotionally ready then there's no point in forcing it. It only leads to stress for her parents and for her - and the more stressful things get, the less likely she is to want to use the potty. We tried bribery (the chocolate stayed in the jar until it went past its sell-by date), star-charts (she enjoyed making it, but it made not a blind bit of difference) and everything else you can name - nothing worked because she simply was not ready emotionally. In the end it was nicer for all of us to do things on her terms until she felt ready to try. If you make an issue out of it, it will become one.