So the grandparents married in Russia, and two of their children were born, married and died in Russia?
Once in Australia were the grandparents able to keep in touch with these two children and their grandchildren who remained in Russia?
Did the grandparents come to Australia with any other children? Presumably they were too old to have produced any more in Australia?
Not that the answers to any of these questions will help you at all, but I'm just curious.
I know there is an Australian Russian 'magazine' published which may have been of help in locating family here, or perhaps someone could have advised you about the availability of records in Russia, However, this magazine is just about to cease publication so unfortunately cannot be of any help to you.
Have you tried contacting an archives, town hall or similar in Blagoveschensk? They might be able to point you in the right direction to finding births of Ivan and Anna which may lead to clues about Vlas? Of course it is possible that no records survive even if they once did exist.
