The phrase "to expand the list" means to add more things or items to an existing list in order to make it longer or more comprehensive. Full definition
In today's world of integrative medicine there is an ever expanding list of options available to you, and it can get quite confusing. (wallerwellness.com)
I recommend you use these job boards to create a target list of companies in your area who are 50 + friendly, by expanding the list as I've shown above. (recareered.com)
The next task is to expand the list by finding out if the agents you have listed are reliable. (readersfavorite.com)