In her post "Full or Half Siblings" on DNA Explained (posted 3 Apr 2019), in the section Unusual Circumstances, Roberta Estes says:
These cases tend to be quite messy and should be unraveled with the help of a professional.
and at the end she gives wise advice:
Regardless of the genetic outcome, I hope that you’ll remember that
your siblings are ...
You do not say whether you have considered AncestryDNA but the autosomal DNA test available from that company can be used to look for East Asian Ethnicity:
People in this DNA ethnicity group may identify as: Russian, Chinese,
North Korean, South Korean, Mongolian, Vietnamese, Burmese (from
Myanmar), Japanese, Taiwanese, Filipino, Indonesian, Thai, Laotian,