DAX LOOKUPVALUE looking in multiple tables

Question

I am pretty new to DAX/PowerBI.

I have 3 separate tables, each contains Account Name and Account Number columns.

I already created a 4th table (a derived table of the other 3 tables) showing Account Numbers only once by using DISTINCT/UNION/VALUES. This worked well.

Now I want to bring in Account Name for each unique Account Number onto this 4th table.

I was thinking of using LOOKUPVALUE, but I need it to somehow look up Account Name:

1. in the union of the 3 separate tables' Account Name column
2. in the union of the 3 separate tables' Account Number column
3. per the Account Number shown in this 4th table

Can this be done? I am struggling to write the criteria for 1. and 2.