Share Point Designer – Can a workflow take multiple row data from one list and transfer it to a search column from another list?

I have a list of organizations and a list of contacts. Contacts are linked via vlookup to the list of organizations. I want all contacts associated with a specific organization to be listed in the list of organizations. I have not found a solution that allows a workflow to do this directly because the search function only captures the first instance. My solution is to establish the connections in Excel. Using concatenates, I can combine all the contacts associated with an organization into a cell. I could just paste the Excel results into the list of organizations, but there are several thousand organizations and SP only allows you to paste 100 rows at a time. I had the idea to create a third list entirely text-based so I could use Access to bulk paste, then use a search workflow to connect contacts to organizations with the column containing the names of the contacts as lines of text separated by one; converting to a search column the contact names of the contact list. In this way, other contact information could be transferred to the list of organizations. The problem is that I can not create a workflow that can do this.