Just to be clear, are you asking to have (4) levels for grouping in the "Estimating" software or the "Database Editor (DBE)". If in Estimating, then yes, use WBS codes and Item sorting. But if in DBE, then that is only Group phases/Phases/Items. 

To setup WBS codes, in the database settings you'll need to set up a wbs code for each CSI level. Once you make a CSI WBS code, for example: "CSI Level 1" (you'll have to abbreviate the description a bit in the software) at that point, you'll then have the ability to make a drop down list of over 65,000 choices for that WBS code. So, setup wbs codes for CSI L1, CSI L2, CSI L3, CSI L4. Then those new fields will allow you to assign values to each item, such as:  "03 00 00.00" for Concrete L1, and then CSI 2 would be 03 30 00.00, etc for CSI 3 and CSI 4. You'll use DBE to assign those values since you can Fill Down in DBE (for L1, L2 and maybe L3). 

After you have the WBS Levels 1-4 assigned to the items, you can then sort the DB by those WBS Codes and you'll have (4) levels of Folders. Good Luck!

Thank  you for this response. I think this is the path I'll need to take.

This make some sense to me. But in not dealing with WBS codes before I am having some issues. I went in to my estimate to Database-->Database Settings-->WBS. There are only 40 spaces here, so I assume I can only use "Tier 1" items here (03 00 00 Concrete, 04 00 00 Masonry, etc.). I am limited on characters so I abbreviated these to 03-CONC, 04-MASON, etc. 

From that point, I am lost. Where can I make this drop down list and how would I tier those?

Also, what do I list under the "Type" (Takeoff, Item, Detail) and what does that do?

You'll want to set up the WBS in Database settings like this: Description: CSI L1, Type: Detail. Leave Size and Unit alone for now. (so NOT actually calling it "03 00 00 Conc,", etc, that will happen on the ITEMS)

Now, go to any ITEM in the database and the above steps will now have ADDED a new field to that Item (click the WBS button to see CSI L1)!

That is basically where you will make the drop down list. Each "ITEM" will then be able to have "03 00 00 CONCRETE" or "04 00 00  MAOSONRY" for the Value and Description of the CSI L1 WBS code on that particular ITEM.

Repeat the above for CSI L2, CSI L3, Etc.

You'll want to set up the WBS in Database settings like this: Description: CSI L1, Type: Detail. Leave Size and Unit alone for now. (so NOT actually calling it "03 00 00 Conc,", etc, that will happen on the ITEMS)

Now, go to any ITEM in the database and the above steps will now have ADDED a new field to that Item (click the WBS button to see CSI L1)!

That is basically where you will make the drop down list. Each "ITEM" will then be able to have "03 00 00 CONCRETE" or "04 00 00  MAOSONRY" for the Value and Description of the CSI L1 WBS code on that particular ITEM.

Repeat the above for CSI L2, CSI L3, Etc.