There are three influences here that will impact on the situation. Firstly, they become to the age of teenagehood. Your frustrations are that of most parents, who have seen their kids growing with the discipline and principles they spent years instilling with pride going all down the drain in a matter of months and thinking where they went wrong! Yes, teenagers suddenly lose their manners, lose all notion of appreciation and suddenly seem to think they don't have to do as told. That's par to dealing with teenagers and involves taking a massive step back and going back to basics telling them off and reminding them of rules/manners etc... Then one day, they suddenly turn into lovely young adults, pointing out other's bad manners (had to laugh when DD came back from work one day telling me how she really hated people not saying thank you!), and actually asking you about your day!
There is then the issue of them feeling that coming to you is a break from the strict discipline they get at home. In a way, it is quite nice that they feel this way, however, it certainly shouldn't mean that they get a full on holiday. They will take the attitude of what they can get away with! There should be a minimum of rules that apply just as they do at their mums, tidying up their room for a start.
You do say they reacted well to you asking them to do things, so I would go with the flow. As long as they do what you say but still come to you for things, still talk to you about their lives, still come and say hello when they first come in, then clearly they are not taking it as you being only the bad cop and accepting your disciplining.
Then you have the issue of consistency amongst all the children. More difficult when the children are of similar age, but when there is a gap, then it is easier to manage, how there would be differences anyway even if they were living in the same household.