I think the text message is a great idea. However - I have family who would think it doesn't apply to them. Would yours fall into the same category? "Oh - she doesn't mean us!!! We'll just pop round for a quick cuppa..."

So you need to be prepared to maybe deal with that. Like - sign on the door, but again, they might think they are exempt... so maybe DH needs to be prepared to deal with unwanted visitors! To be strong and say "Now really is not a good time. We will see all our family at the BBQ/pub/whatever on x date."