My in-laws lived with us for more than 6 months last year and we need to declare them as dependent. From IRS website, it seems that all we need to do is fill out a W-7 form and notorized Passports, attached them with tax return documents and send these material to W-7 special unit mail box. My questions are:

1) besides the mail to location that specified in W-7, should the tax documents (1040) be sent to any other locations?

2) On 1040, we should write their information under dependent section, right?

3) Is there any thing else missing?

If anybody knows, please help.