As above except for the fact that I would always request that if enough cabin crew available I would request that one stays on the flightdeck purely in the role of observer just incase I too then keel over due to the stress of it all. I would be very unlikely to try and get them to actually play any part in the operation unless I had knowledge that they actually had some relevant experience, suprising how many crew I fly with that have atlease a ppl/cpl/atpl.