1. A method for execution by a computer, the method comprises: determining, for a set of user devices, access performance of a copy of copies of dispersed storage encoded data, wherein the copies of the dispersed storage encoded data are stored in a set of dispersed storage networks (DSNs), wherein a DSN of the set of DSNs includes a plurality of dispersed storage units and is storing the copy; when the access performance is not at a desired access performance level, modifying, at least one of a set of user devices assignment to the DSN and the set of DSNs based on the access performance and the desired access performance level; and when the set of DSNs is to be modified by adding a new DSN to the set of DSNs, for the new DSN: determining error coding dispersal storage parameters based on local data retrieval accesses allocated to the new DSN; facilitating the new DSN storing another copy of the dispersed storage encoded data and changing assignment of the set of user devices to the new DSN for accessing the copy.