Realistically one donkey would never have been enough. Mary and Joseph would need buggy, car seat, sling, nappies, wipes, vests, babygros, shawl, muslins, cardies, snowsuit, Moses basket and bedding (they didn't know there would be a manger available), intercom, room thermometer, mobile, teddy bear etc etc. Depends how influenced they'd been by Mumsnet, Mothercare, NCT friends but no way would even the basics fit on the average donkey along with a 40 weeks pregnant woman.
I only hope there was room in that stable for all the cards and "IT'S A BOY!" helium balloons. At least the keyboard could double as a changing table.