On-boarding federation allows an enterprise to efficiently migrate its data from one storage cloud provider to another (e.g., for business or legal reasons), while providing continuous access and a unified view over the data during the migration. On-boarding is provided through a federation layer on the new destination cloud providing delegation for accessing object on the old source cloud. In this paper we describe a delegation architecture for on-boarding where the user delegates to the on-boarding layer a subset of his/her access rights on the source and destination clouds to enable on-boarding to occur in a safe and secure way, such that the on-boarding layer has the least privilege required to carry out its work. The added value of this work is in evaluating all security implications of a delegation necessary to be taken into account during the on-boarding phase. We also show how this delegation architecture can be implemented using Security Assertion Markup Language.