have got email from another school mum suggesting a joint party for our dds 5th birthday party. Basically it suggests I join her and her friend for a joint party. So far so good only my dd was 5 in June and her and other mums dds are 5 in sept and oct. They have said party will be on x date and at x place. Decision made. Am I unreasonable for thinking they just want me to get chequebook out for a third of cost?!