from IRS pub 502 medical expenses
they would have to meet the tests for qualifying relative
A qualifying relative is a person:
1. Who is your:
a. Son, ,
2. Who wasn't a qualifying child (see Qualifying Child, earlier) of any taxpayer for the tax year and
3. For whom you provided over half of the support in the tax year
the following tests for qualifying dependent ate waived for purposes of deducting their medical expenses
He or she received gross income of $4,200 or more in the year.
He or she filed a joint return for the year.
it would seem you don't actually claim them as dependents.
from another thread
taxpayer is claiming non-dependent (medical expenses for the medical treatment I paid for son . Is this allowed by the IRS?
Exceptions exist for claiming non-dependent medical expenses on your tax return. The exceptions allow you to claim medical expenses of someone who is not your dependent. You can claim an exception for any of these people:
An individual you would have been allowed to claim as a dependent except one of these applied:
He or she received gross income of $4,200 or more in the year.
He or she filed a joint return for the year.
You (or your spouse if married filing jointly) could be claimed as a dependent on someone else’s return in the current year.
the expenses would still have to qualify as medical expenses
see irs pub 502
