When my nephew was a toddler/pre-schooler, he had major separation anxiety issues and tantrums. Specifically, whenever his grandparents or we (his aunt and uncle) visited him, he'd never let us leave in peace. He'd cry, follow us out of the house, throw tantrums - the entire production. It'd always delay our plans by half hour to one hour. His parents never objected to this behaviour, in fact, I think they even supported it because they found it adorable and/or amusing.
Around 4 years later, we have a 3 year old daughter. She loves it when her extended family comes over, and has a lot of fun with them. But doesn't throw a tantrum when its time to leave. (I think we've raised a sensible and well balanced child) She sometimes asks once or twice if they (or we) could stay for a little while more, and if we say they (or we) can't, she understands.
The grandparents though, seem to misinterpret this as lack of attachment. They told my daughter that when her cousin was her age, he loved them so much, he'd never let them go so easily, that he'd really miss them if they went away, and that he'd often ask for them in the night if he wasn't able to sleep. (That, according to me, was just lack of discipline and sleep training!) I assured them later that she misses them just as much, but just understands that they have to leave. I don't know if I convinced them, but that's the least of my concerns.
When our daughter spoke to us after they left, we found out that they've said things along these lines a couple times before too. She feels really hurt that they think she doesn't love them as much as her cousin. A tearful "Does [bob] love them more, daddy?" broke my heart. I told her everyone loves everyone else the same amount, but have different ways of showing it. I thought that was that, but she seems to have learnt the lesson that the way her cousin showed his love was better. And she actually did cry a lot and told her grandparents not to leave the next time they visited! This has never happened, I've never had more than a pouty face, and nothing I couldn't fix with some explanation and some distraction. But this time she didn't stop crying till the grandparents agreed to stay for 1 more hour.
I'm at a loss now, how do I handle this new development? I don't want to tell her that its her cousin's and his parent's behaviour which was wrong until I absolutely have to. I don't want her to "learn" separation anxiety, nor get her way with her grandparents by crying. I could convince them not to stay back just because she's crying, but would that confuse her more? Would she feel that she can't win their favour no matter what she does?