I have 2 very fussy youngest sons-even at 18 &22- its about the textures of some foods for some kids- id stick to what they already know and love, not bombard with 'new' stuff, it might put them off wanting to come stay again! Certainly ASK them if theres anything they particularly want, or might like to try, but if they just want 'their usual' don't push it- at least you know they won't go hungry if they eat what they do at home.Sadly, staying at granny's doesn't make kids miraculously adventurous overnight.In our family we also have a few kids with food allergies, thats a whole different problem too- But my fussy sons aren't allergic, just have their own taste/texture choices, youngest now likes smoked salmon, anything chicken, bacon, pepperoni, likes pesto, won't have potatoes unless they're chips.Neither son has gravy or sauces.etc..If they don't want to try any new foods, just stick to what they do want.if you do try the 'snacky plate' idea, don't cajole or berate them if they don't want it.Maybe next visit they will have expanded their own choices.?