How do you make a word like "parent(s)" possessive? [duplicate]

Possible Duplicate:
What is the correct possessive for nouns ending in s?

"Please submit your and your parent(s)' federal tax returns." Is the possessive of "parent(s)'" correctly formatted in that sentence? I know the apostrophe comes before the "s" for just parent singular, and it would come after the "s" for parents plural, but what if I don't know if it is one or two parents, and therefore want to use the (s)?

Solution 1:

I take it based on the content of the sentence you are not so worried about technical grammar, and more concerned about unambiguous communication. I think if you leave it the way you have it, the intent can only be interpreted correctly. That having been said, it is obviously not precisely right because omission of the (s) doesn't leave a grammatical remainder. If you want to be right without question (though a little stilted) use some thing like: "Please submit the federal tax returns of yourself and your parent(s)." or "...your tax return and that of your parent(s)." In the second last example, replacing 'of' with 'for' sounds a little better but is slightly less precise semantically.

Solution 2:

Perhaps

Please submit your individual and parental federal tax returns.