"My siblings are eating dinner."
Translation:Moje rodzeństwo je kolację.
Could you explain this (or link to an explanation) a little more in depth? I realize that the word used is singular. As a non-native speaker, I am not yet familiar with how to know when neuter words should be kept singular even when referring to multiple people/objects. For example, I don't think you would say "Moje dziecko je śniadanie," when you actually mean that your five children are sitting together eating breakfast. (Or maybe you would say that?) So, that is why we are confused about this one. :-) For English-speakers, a sibling may be eating breakfast or many siblings may be eating breakfast. Is there a way to know when this distinction is not necessary beyond the fact that the dictionary form of the word is neuter singular? I hope my question makes sense. :-/
"Państwo je kolację" is actually grammatically correct. It just means "The state is eating dinner".
I think that possibility prevents natives from ever making such a mistake.
Also, państwo in your example is a pronoun, which is a different word type than a noun, so different rules are likely to apply.
"rodzeństwo", although it's a singular noun, almost always refers to more than one person, i.e. "siblings".
It could potentially mean just one "sibling", but that seems rare, it's a lot easier to say "brat" or "siostra" then. So it's most common when you have siblings of both genders.
Isn't it strange that Odmiana.net ( http://odmiana.net/odmiana-przez-przypadki-rzeczownika-rodze%C5%84stwo ) considers the declinations as "liczba mnoga"? I mean it takes singular verbs and even the endings are singular (-em and not -ami in Narzednik, etc.).