Creating a new index or modifying an existing index which is best option

Hi All,

I have received a request from a customer having issues when he is executing a function, when i checked the details and executed the function by using theinclude actual execution plan option, there was a missing index on of the tables namedweb_function which has columns like projectid, linkid etc..and index was being recommended on both the columns as below from execution plan, but the issue here is there is already a non-clustered index on columnprojectid.

How should i proceed further on this, whether i have to modify an existing index and add column linkid to the existing index or create a new index, which of it is the best way to proceed?

Please advise.

CREATE NONCLUSTERED INDEX [<Name of Missing Index, sysname,>]
ON [dbo].[web_function] ([projectid],[linkid])

Thanks in Advance.

Regards, Kranthi