it is still confusing, but I already understand more details.
The confusing parts are the fact that you use "export from" (which should probably mean import from or export to) and also you use "vendor" in one sentence as a third party and in an another sentence you say "but as vendor i just have" and " as vendors i will "
So it is unclear if your client is the vendor or you client is buying from an external vendor , then why do you want to control what your vendor does?
Isn't it just enough if you vendor tells you on the papers that 40% of the material has an US origin and 30% are with HK origin and 30% with SG origin?
Or is it the case that you order at a US vendor, but the vendor distributes your order to various of his subsidiaries and you get 3 deliveries coming from different countries?