Queries :: Compare Data In 3 Fields In 1 Table / Group By Largest

I'm trying to create a query that will compare the data in 3 fields in a record, choose the largest (I also have a criteria to order by if more than 1 field has the same entry and it's the largest of the 3), and then group by that.The fields I will need are as follows:

PRODUCT table:
ProductName
Chemical
ChemicalAbstract
PhysicalState
NFPAHealth
NFPAFlammability
NFPAReactivity

qryQuantityOnHand query (which doesn't link directly to the PRODUCT table, it links through associations with other tables):QOH...I will eventually need information from another table for the final reports, but I don't think it has to be included in this query.

The fields NFPAHealth, NFPAFlammability, and NFPAReactivity each may be 0, 1, 2, 3, or 4...I need to ignore blanks; if 1 of the above fields is blank, they will all be blank.For any record, I need to compare the number in those 3 fields to each other, and choose the largest number and group by that rating.

In other words, if the largest of the 3 numbers is a 3 in the NFPAFlammability field, all those products need to be grouped together.If the same number appears in at least 2 of the fields, the order that determines the grouping is: Flammability, then Health, then Reactivity..Ultimately the report will be grouped as follows:

Flammability
Rating 4
Product 1
Product 2
Product 3

Rating 3
Product 1
Product 2
Product 3

Rating 2
Product 1
Product 2
Product 3

Health
Rating 4
Product 1
Product 2
Product 3

[code]....

and each of the groups will be sub-totalled.I'm stumped at trying to create the query in the first place.The added aggravation here is that we are dealing with 23 stores, each with their own mix of products. I have another table that contains the information about which products are in which store.