Dynamic priority list Excel

So I'm trying to come up with an automated system to help me create a dynamic two level priority list. I'm not sure if this is possible, but I'm crossing my fingers that someone will come up with a creative solution.

Let me know if I can help clarify anything.

So given the following setup:

• Scenario 1: When user adds new item [assume as new row at bottom current table] they can specify overal category [using data validation for low/medium/high]
  • Within priority will be assigned as last number in that level. For example, if Project I is added as low priority within priority will be 4
  • Table will then be sorted by overall priority, then within priority, then project description
    • flexible as to whether this is done in a linked table in separate tab or within same table
  • User can then alter the within priority level
  • Program should renumber list as needed [so if new item is within priority level of 2, previous level 2 will be changed to 3 and so on]
  • Program resorts [either same table or linked table in separate tab] by overall priority, then within priority then project description
• Scenario 2: User changes overall priority and/or within priority
  • If change overall priority
    • Automatically change within priority to last number in within priority list. For example, if Project E is changed to low priority it will be given within priority of 5 [assuming inclusion of Project I as mentioned above]. Also, the level the project left [medium] is renumbered so there are no missing values.
  • If change within priority
    • Program resorts [either same table or linked table in separate tab] by overall priority, then within priority then project description