If there are other life forms that can get to us, they must be far far more advanced than us, so it's fair to say they could perhaps nip here and nip back without us knowing. But I doubt they'd ever need to abduct one of us. And if they did, they certainly wouldn't need (or perhaps want) to return us at a cost of extra billions of space pennies. lol
They would probably stay, once they'd sussed out the benefits system!!! And then bring their families or claim for their 'androids' living in another galaxy!