UFN_REGISTRANT_GETNAME

            CREATE function dbo.UFN_REGISTRANT_GETNAME
            (
                @ID uniqueidentifier
            ) 
            returns nvarchar(700) 
            with execute as caller
            as
            begin
                return (
                    select
                        case when REGISTRANT.CONSTITUENTID is null
                            then 'Guest of '
                            else ''
                            end + NF.NAME
                    from 
                        dbo.REGISTRANT
                        left join dbo.REGISTRANT as GUESTOF on GUESTOF.ID = REGISTRANT.GUESTOFREGISTRANTID
                        outer apply dbo.UFN_CONSTITUENT_DISPLAYNAME(coalesce(REGISTRANT.CONSTITUENTID, GUESTOF.CONSTITUENTID)) NF
                    where 
                        REGISTRANT.ID = @ID
                )
            end