Tips to help ex-feral deal with company

I have had company before but it has been for two nights max.  This time my sister and her daughters will be staying for a week.  We will be out of the house most of the day at another relative's house so they will mainly just be sleeping and showering at my house.  I have three cats and they accept company in varying degrees, Stilton loves having extra people to give him attention, Nacho hides the first day but then will come out and be in the vicinity of the new people and is ok as long as no one approaches him but Cheddar, my ex-feral, is inconsolable.  All night long he jumps on and off my bed letting me know he is not happy with the situation.  When I get up in the morning he wanders around meowing until he hears someone get up downstairs, at which point he hides under the sofa.  The thought of having a week of this, and getting very little sleep, is not appealing.  Does anyone have any suggestions to help Cheddar calm down?

Have you ever tried any flower essences such as Rescue Remedy or Composure calming treats/liquid.  I found composure liquid max very helpful for my ex feral I brought inside.  I would give 1/2 t. ( doubled the amount which can be given during stressful times) during the most stressful time of the day and then another 1/4-1/2 t. later in the day.  I mix it into wet food in the morning meal and then again for the evening meal or instead give a small snack an hour or so before bedtime with the composure.  My boy didn't care for the treats and it took a lot of treats.  I believe it was 3-6, 2x a day.  The were kind of hard and chewy.  The liquid was much easier.

Also do you use Feliway diffusers?  It is important to have them scattered throughout the house and to begin using them before company comes.