Can we create a two or more column table in BPM Global variables?

Summary:

We have our Req. approval rules in BPM. Our requirement is to determine approval rules based on 2 parameters for examples -

if cost center is 123 and BU is 456789 then it should go to Approver A

if cost center is 123 and BU is 789123 then it should go to Approver B

Here BU value is not available in fusion. Hence we cannot directly fetch it using BPM attribute. So, I guess we would need to create and maintain this Cost Center and BU mapping somewhere.

I would like to seek your advice / suggestion - what would be best place to maintain such mapping while using rules in BPM? Does Global variables in BPM support such mappings? If not, where else can we save this table and fetch values of 2nd column against the 1st column?