Breth It could be that the elder child really enjoys nursery and that mum a) wants to disrupt his/her normal,enjoyable routine as little as possible and b) is glad of time spent with the baby and getting a little bit of breathing space before she has to cope with both baby and an active pre-schooler simultaneously. Even if the older child is in the nursery "full-time" he/she probably still gets a fair amount of time with mummy and, presumably daddy. You say that she is a professional woman and if she's that eager to get back to work she must enjoy her job. Someone's profession is an influential part of how they see themselves and evaluate themselves. It's quite a difficult juggling act and it's difficult for anyone outside the family involved to understand exactly what's going on in detail and to see the bigger picture. We all have to sort out our own priorities and, of course, sometimes we get things wrong. I don't think there are many women having babies (plural) these days, when it's avoidable, who don't have any maternal instinct, but I suppose it's possible. This couple are fortunate in having you as substitute parents and as you have done this already for five years, I suspect you will have no trouble in carrying on – and that, I think, would be the best and kindest thing you could do.