In the seventh book we are introduced to the “trace”, a means by which the Ministry can track underage magic. Yet this is at odds with earlier books where the Ministry is not able to determine if an underage wizard did magic; they can merely determine that magic was performed in a certain place (e.g. Dobby in the beginning of the second book).
Shteit ?????, that the trace can detect magic performed in the vicinity of an underage wizard, but not who by. This is why it was why at the beginning of ‘??? ? they are unable to transfer Harry through spells, as casting spells, even by overage wizards, would result in activating Harry’s trace. Therefore they used modes of transport upon which the trace didn’t work i.e. charmed objects such as brooms and potions. So in the case of Dobby, it would be traced to 4 Privet Drive.
And yekke2, old question. Pashtus PAA is right, although it’s not so ????, especially as all the Elves are doing is picking them up. So Dobby in his time at the Malfoys could have just picked up some clothes. And can all House-Elves not work with clothes? ???? its ???? on ??? ?????.