SSRS: Display a different word (alias) in parameter than that in login domain

I am creating a report for several related companies and using the user's login domain to restrict the data to thier specific company. The problem is that the domain doesn't match the company name. I need to display the company name in the parameter to eliminate confusion as to what they are seeing, especially for the users that login using multiple domains. Is this possible? If so please provide some instructions.

I am using the following statement to pull the domain: =Split(User!UserID, "\").GetValue(0)

EX: domain/login like xyz/bsmith, but i need to display ABC instead of the domain xyz
domain/login like mno/ajordan, but I need to display JKL instead of the domain mno

I do have a table that contains the domains and company names, or I can create a join between tables to do the same thing.

I may be searching for this the wrong way, but I can't find any questions like this issue.

Googled several related phrases, as well as attempted to search inside stackoverflow with no success.

I'm not sure if I understand what your problem is as you already have a table with the domains and company names so just create a dataset called say dsCompany with a query something like

SELECT Company FROM myTable WHERE DomainName = @userdomain

This should automatically add a userdomain parameter to your report, but in case that didn't happen, just create one (they are case sensitive so check spelling) then set its default value to

=Split(User!UserID, "\").GetValue(0)

If this does not help, please explain the scenario in a bit more detail, mock up some images of what you expect the users to see etc..