I manage a Seniors community. Some of my residents have a really hard time when I tell them No, I think it's because they have grandchildren older than me
This conversation has happened more than once, and usually does the trick:
Resident asks for something that is agains policy;
Me) Sorry Mrs. Jones, but I can not do that as it is against our policy
Resident) But...
Me) if your neighbor wanted me to allow her to have 2 large dogs should I?
Resident) Certainly NOT!
Me) and why not
Resident) because the rule says...xyz
Me) But if I change the rules for you why shouldn't I change them for your neighbor?
Most of the time this ends the conversation!