a.I saw my houses which had been destroyed by the storm.
b.I saw my houses, which had been destroyed by the storm.
Some days ago, I wrote (a) and Amy have corrected into (b). I’m surprised that not only Amy but most of English people, when seeing my sentence, have corrected into (b).
For me:
In a: means some houses of mine.
In b: means all of my house.
I think my initial sentence is not strictly ungrammatical. Amy, if you are free, please analyse the situation so that I can see the difference btw them and the reason for that you have changed my sentence.
Please have a look at some material I’ve written for the site on relative pronouns - particularly on the difference between defining and non-defining relatives.
When you leave out/omit the comma before ‘which/who’ you are defining/describing the previous noun(s). When you put in/insert the comma before ‘which/who’ you are not defining/describing the previous noun(s), you are adding extra information.