She'll be flirting more with S than she will Joshua.
Wilby staying at his grans is fine. At 5 it was loved to go visit gran for sleepovers. But only if THEY wanted to.and not to palm off when we didn't want them around. And I can't think of one time inviting some kids and not the other. Especially when younger.
Bloody hell 30 years later my own parents still invite us all if it was more a "holiday". or if it was arranged off the cuff after just speaking to one of us,or one sib was seeing our parents. us others would always no we were welcome. It's never ones invited over the others ever. That's now, it certainly never happened when we all still lived at home.
I find it ridiculously funny to even try and imagine my mum coming in and saying " right we are taking your sister away.your staying here ok." duck off.