Check out some of the links here: https://www.google.com/?gws_rd=ssl#q...pouse+expenses
I looked at 3 and they all said you could pay for other family members out of your own account (and the reverse). Having multiple sources agree is almost as good as getting it from IRS; might be in Pub969 but this seemed easier.
and here's P969:
Qualified medical expenses are those incurred by the following persons.
You and your spouse.
All dependents you claim on your tax return.
Any person you could have claimed as a dependent on your return except that:
The person filed a joint return,
The person had gross income of $3,950 or more, or
You, or your spouse if filing jointly, could be claimed as a dependent on someone else's 2014 return.