Thank you for your new question and for asking for me.
Legally, an idea cannot be protected by copyright or trademark. Only an actual tangible item can be protected by trademark or copyright. It is for this reason most large companies will refuse to take unsolicited ideas. The only way to "protect" your idea is to discuss it vaguely with the restaurant chain and if they are interested, before you disclose the idea itself with them you would have them sign a non-disclosure/non-use agreement. However, most companies will just blow you off and would not be interested in the idea at all because they do not want to sign such an agreement I am afraid.
This is a real issue for people who come up with ideas because companies will not want to sign a non-disclosure/non-use agreement and the people cannot present their idea and try to protect it without one. It is a catch 22, sadly that all you can do is try to pitch the concept without disclosing your actual idea and try to then get them interested enough to sign the NDA.
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