LOA169
However to have access in the first place you still must satisfy one of the criteria that permit access (over and above being approved by the PIC).
You have only got to meet those following criteria if someone enters the cockpit after take-off. If someone enters the cockpit before take-off then it isn’t applicable. Infact the whole regulation isn’t applicable. Having said all that one may run into trouble if the said jump seater/s need to use the toilet during flight. Under the letter of the law they may not be able to get back into the cockpit.
At the end of the day what's in a company’s Ops Manual will determine who can ride the jump seat. I would say most companies would be more restrictive than the regs.