if it were me i wouldn't make a big deal of it.... when my dd goes to my parents house to be looked after, we just tell her she is going for a visit... sometimes she asks if it will be a little visit or a big visit, and we will say either big or little, but thats about as far as we go... once we left her for a weekend away and my mum just said we were at work, and would be back soon.... they don't need to be bombarded with huge amounts of detail, and the less big a deal of it you make the more accepting they will be.... sometimes work goes for a long time, sometimes for a little time... simple.