Is it possible to add on 'basic issues search' page into drop-down 'Assignee' returns of custom JQL

[Роман Кузнецов]

I wrote a JQL function that returns a list of users sorted by roles. That works like this:

assignee in role("user_role");

I need to enable to work with this function from the GUI, namely, in drop-down lists in which users search by groups and nicknames, add search by roles.

Is it possible?