Most airlines have a weight limit of about 20 kgs per passenger, which is OK for a holiday (for some) but it is not a lot for someone migrating, who may need a few more things than most holidaymakers.
There is often an option given by some airlines, where they give an extra allowance (sometimes double, 40kg) for people migrating.
You do NEED to ask the airlines, and get it in writing, so that you have no last minute hassles at the airport check-in.
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