Currently my parents are residents (none-citizens) do not have any health insurance and no income.
I paid for several of their medical expenses in the US and outside the US. Can I use the HSA account to pay myself back?
Will the answer change if at some point they enroll into medicare/medicaid?
Not unless you can claim them as dependents.
Whose Medical Expenses Can You Include?
You can generally include medical expenses you pay for
yourself, as well as those you pay for someone who was
your spouse or your dependent either when the services
were provided or when you paid for them. There are different
rules for decedents and for individuals who are the
subject of multiple support agreements. See Support
claimed under a multiple support agreement, later, under
A qualifying relative is a person:
1. Who is your:
a. Son, daughter, stepchild, or foster child, or a descendant
of any of them (for example, your grandchild),
b. Brother, sister, half brother, half sister, or a son or
daughter of any of them,
c. Father, mother, or an ancestor or sibling of either
of them (for example, your grandmother, grandfather,
aunt, or uncle),
d. Stepbrother, stepsister, stepfather, stepmother,
son-in-law, daughter-in-law, father-in-law,
mother-in-law, brother-in-law, or sister-in-law, or
e. Any other person (other than your spouse) who
lived with you all year as a member of your household
if your relationship didn't violate local law,
2. Who wasn't a qualifying child (see Qualifying Child,
earlier) of any taxpayer for 2017, and
3. For whom you provided over half of the support in
2017. But see Child of divorced or separated parents,
earlier, Support claimed under a multiple support
agreement, next, and Kidnapped child under Qualifying
Relative in Pub. 501.