score:3
There are some routes where this is applied; for example from the ME to Asia there are special exceptions on luggage weight on some airlines (Kuwait Airways, for example).
A few airlines I have flown on before have such allowances; but I have only heard of them for students and repatriation; but not for immigration and then not between those two countries specifically.
A while ago, there was some hope:
Singapore Airlines offer a double baggage allowance (from the usual 20Kg to 40Kg) providing you are holding an unused migrant visa that states to remain in Australia indefinitely. If you hold a valid visa, you will be entitled to the double baggage allowance on production of the visa at check-in.
However I cannot find this reference anywhere on the current website.
Upvote:1
I have never heard of such an allowance on all flights from a given airline. However, while I don't remember the specifics, I did hear about some specific routes where extra luggage was allowed in some cases (and Tom mentioned another one in a comment). Consequently, rather than a list of airlines, it might be useful to scour the net for forum posts, using the departure and destination and “emigration” or “luggage” as keywords.