Hello JA Customer,
I assume you are married filing a joint return, and these are your spouse's parents that you want to claim on your return. If that is the case, there is no requirement that they lived with you at all.
To claim someone as a qualifying relative, if they are related to you in certain ways, then there is no residency requirement. There is a requirement, however, that they cannot have had income of their own of more than $3,650 each for the year. SS benefits are not included in that calculation. As long as their income did not exceed that amount and as long as you provided for more than half of their support, then you may claim them as dependents. If they are also claimed by someone on a Canadian tax return, that has nothing to do with IRS requirements and does not prevent you from claiming them on your US tax return.
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Thank you JA Customer