Please have patience with the children. It is quite normal for children not to instantly receive you with open arms; it may take them a few weeks to get used to you. Don’t get offended if the child starts to cry if he or she is left alone with you in the first week. For children, a new person within the family is a huge change. After a couple of weeks they will probably accept you as a new family member and by the time that you will be leaving again they will probably have gotten attached to you so much that they will cry again - this time because they don’t want you to leave.