If both CSAs are assigned to the whole book, I suggest using the priority information bc the task list can be sorted based on priority. You can create template activities, ie. recurring tasks like money movement (high priority, #1), account opening, etc. and assign a priority for ad-hoc tasks and also assign both CSA's and to Rachel's point the high priority items are tackled first based on bandwidth (remove the other CSA when you've started a task). If your CSAs are connecting with clients however, it may be better to have them assigned so the client knows their team. In that case, I would try to divide the book based on complexity and service level. For example each CSA receives an equal number of complex and/or high service required clients so they feel equally fulfilled.