Are these sentences correct:<br/><br/><span style="color:#ff0000;">1) I hired a private detective to watch them so that they would be safe.</span><br/><span style="color:#ff0000;">2) I hired a private detective to watch them for them to be safe.</span><br/><br/><span style="color:#ff0000;">3) I hired a private detective to watch them to be safe.</span><br/><span style="color:#ff0000;">4) I hired a private detective to keep an eye on them to be safe.</span><br/><br/>I think '1' and '2' work. I have doubts about '3' and even more about '4'. They are supposed to mean the same as '1' and '2'.<br/><br/>Gratefully,<br/>Navi.