My helper took my big colourful umberlla,green one & told me she didn't know which one I mean. She still use mine & I gave her a raincoat & kept one in my car & one in my bathroom. Eveytime I ask her to find me one, she will give me the $10.00 one not the $40.00 one, then I go to change on my own.
Comminication is very important. What you want or not want them to do, so called "rules", simply say it out. Once you tell them which umberlla cannot be used, I think they will not use anymore unless they don't want to do la!! A good suggestion is that you assign 1 specially for her. So everytime, she will use her own only.