is there a way to partially receive a transfer order that was fully fulfilled? Every time i try to do that i get an alert saying that I am not allowed to receive less than i have fulfilled.

What is the use case for partially receiving a fully fulfilled transfer order?

when we send out items to amazon warehouse (FBA), they do not receive all units that we send out. So basically, the transfer order is fully fulfilled but partially reveived

So you lose some on the way?

exactly

You can if the Use Item Cost as Transfer Cost checkbox is false. The differences will need to be reconciled and the gl impact on the IF could be off as well and hit your sales account.