Tricky one- I would ask your inlaws first- if she can come and help out? if for example you can delegate her to do 2 families ironing etc etc then that is not a holiday I think you have to pay her but I think you should just be open with her- once you have squared up with your in laws, you should be able to have an open conversation with her- maybe now is a good time to talk about your future holiday plans so she can plan in advance. What has she been doing for the past 6 months in the uk?maybe she has some mates from then? Maybe she would prefer to stay in your house and take it as holiday, or maybe this is the time to ask her if she wants to do things like clean out all your cupboards etc etc. If you are taking it out of your holidays , and you have the same days as her, then you will have to be careful you don't run out of holidays your self. Good luck