How can I restrict the employees list on saved searches when adding 'created by' as a filter for transaction saved search? Ideally I want it to display certain individuals that are part of a team rather than the whole company however unsure how I could restrict who comes up? Any ideas?

You can't restrict, however, you can create a custom field that has the users you are want to be available in the list. Populate that field with the user on creation, and csv import to update old ones. Then use this field as the filter since it has a custom list of employees. Kinda convoluted....but definitely doable if it's required