If someone agreed to do this in order to save multiple postage costs, they would be liable to pay VAT and duty on the entire value of the package and then be responsible for the onward UK postage. These costs would then have to be recovered. I am not sure private individuals could be persuaded to take on this responsibility although I may be wrong. A business might be persuaded but would then need to put their own markup on it further increasing the costs. Good idea in principle though.