My husband's big birthday looms, we are having a meal for his relatives at a relatively expensive restaurant, as a treat and a get together. At first it looked like it was just going to be his immediate family and that we would pay half and his father would chip in the rest (as usually happens). He has also invited his two half sisters (on his sister's suggestion) who are now bringing their partners and children. The total is now around 16 people. We have just realised that we may be expected to pay for everyone (approx £500) We don't have this much money. My husband is embarrassed to broach the subject of who is going to pay. We cannot risk the bill of that amount. I'm on maternity leave and we are skint. We could afford up to £100 but no more. His family is not particularly open or communicative and may have traditional ideas about this. I have no idea what the etiquette is these days. Any ideas or thoughts? How can we solve this cock up without upsetting people?