Disclaimer by nonresident beneficiary

[Guest halka]

Deceased participant designated his sister and niece as co-beneficiaries under the Plan. The sister is a resident of Vietnam and (reportedly) speaks no English. The niece is a US citizen. The sister wishes to disclaim her interest in the Plan benefits. Other than meeting the rules for a "qualifed disclaimer" and perhaps verifying she comprehends what she is doing, are there additional requirements or caveats resulting from her nonresident status??

THANKS