Introductions

We have a seven year old bio boy, and are just going through introductions with a little 4 year old girl. Never having done this before have been surprised at how emotionally draining and difficult it is. My husband and son are really managing it all extremely well, I am finding the process quite scarey as the concept to be an immediate mummy to a little girl I have only just met is hard. Has anyone else found the introductions hard. My friends say I am being too hard on myself as it will take time to bond with a new child. In a way I can understand this as our little boy has been part of our lives for seven years. Any advice, stories, whatever would be really helpful as I know people who have been in the same situation can pass on their own experiences. Wish everyone out there so much luck as I know what a huge emotional journey it is.