When we refer to a house that belongs to a family, we say "family's house". Pluralizing family gives us "families". Referring to the houses of several families, we say "families' houses". Forming the plural possessive in such a case is rather simple.
I encountered a more complex use of this recently – referring to a single house owned by a single family in a set of houses owned by a set of families.
We can say "the families' houses" to refer to all of the houses owned by all of the families.
We can say "one of the families' houses" to refer to one of the houses owned by one or more of the families. In this context, "one of" applies to "the families' houses".
If we were instead to apply "one of" to "the families", and want to refer to the one house owned by "one of the families", how would this be written?
My first though was "one of the families's house", taking "one of the families" as a single noun and appending 's to it. This looks (and sounds) a bit strange, though. "One of the families' house" and "one of the family's house"/"one of the family's houses" seem wrong to me, and I can't really determine the correct way to say/write this.
Is there a definitively correct way that this should be written?
EDIT: To clarify, although I think I made it clear, in this context, there are several families, and each owns one house. The goal of the sentence is to refer to one of those houses without stating which specific house. Example: "The players and their families want to celebrate their team's victory; this will likely entail a party at one of the families's house".
Best Answer
The construct you suggest is rather awkward as you said yourself. The best way to talk about the specific house is to rephrase the sentence and say instead: "...this will probably entail a party at the house of one of the families."