I cannot begin to express how profoundly saddened I am by the loss of (Name of the Child). Please accept my deepest sympathy, and understand that I am always here to help if you need anything.
(Name of the Child) was a very special child, and I was always treasure the time I spent with (Him/Her) and remember (Him/Her) fondly, especially (His/Her) generous spirit and love. I'm sure that wherever (He/She) is now, (He/She) is spreading the same joy. We're all blessed to have known (Him/Her).
I understand that you need time to be able for awhile, but again, I wish to offer my help during this difficult period. Please do not hesitate to call if there is anything I can do.