Large Drop Down Fields

[TaraMc2]

We have about 200+ clients that we have to choose from when starting a marketing project. Sometimes we have to select multiple clients. We are currently using a very large drop down field but each time an end user selects a client, the drop down field closes and they have to reopen it to select another client. This is laborious and time consuming. Before we onboarded Workfront for our marketing operations teams we used a tool called Appian. When we were on Appian it would do a look-up based on a client code within a field. we could apply many client codes to one field.  I know we have lookup fields currently in the tool but it will only bring in one value at a time in one field. Is there a way to source the clients from a data store or excel sheet that could be used as a lookup rather than trying to select from a drop down field? 

[RandyRoberts]

Is this what you're referring to? I have a few like that and I can select multiples and keep scrolling for more without the dropdown closing. See screenshots:

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